Combining food with sex can add what I like to call "kink-lite" to any sexual relationship. Adding something to your sex life that definitely wasn't in the creation plan gives a fun rush, but you're not getting too extreme with things.
Food can make any sexcapade amazing for a host of reasons, but the over arching one is visual. We are visual creatures, so when you're getting ready to whip out the cucumber, keep in mind that presentation is key. You don't need to have Iron Chef skills, but the basic rule is that if you wouldn't put it in your mouth you wouldn't want to put it anywhere else.
We're in college, and almost everyone has a refrigerator, so next time you go shopping, think past munchies and move your thoughts south... nope, even lower--there we go.
Liquids
Seltzer: Seltzer's better than soda for a lot of reasons. For one, I would not waste my Diet Coke on sex. Seltzer's also not exactly expensive and can be used as a mixer in a pinch (and who doesn't like multipurpose food?). Plus, if the soda's not diet, you don't want to get into the problems that food with sugar makes in bed (more on that later). The kick in using the seltzer is in the bubbles, which feel great on your tongue as well as externally. I would say this is more a foreplay instrument, but it can be used for more southern activities as well.
Hot/Cold Tea (but really any drink): The hot/cold trick works best with tea (so you have a bit of flavor) or plain old water. I've mentioned this before, but it's worth taking the time to bring out of your bag of tricks if you haven't used it in a while. Playing with different sensations adds to the pleasure. Whether you're just kissing after you drank some cold water, playing the skin flute or taking an order to go, anyone can benefit from some temperature experimentation.
Ice: This goes along with the hot/cold play. Try any of your usual activities with an ice cube in you mouth, then take it out for a while and keep alternating. If you can't deal with keeping one in your mouth for too long then just keep it in your hand and have some fun. Draw on your partner and let water run where it may. Don't linger anywhere too long, though--you don't want to freeze any necessary parts. That being said, the skin has a lot of nerve endings, so roam far and wide to play with them all--a little water never hurt anyone.
Alcohol: I'm sure this idea has occurred to at least a couple of you, but there are so many better options. Stick to drinking this stuff. You really don't want alcohol on any sensitive tissues.
Alcohol brings up the general rule that any sugary food and drink should be kept external. I won't get into details but it lets bacteria grow that can case some real damage down there.
Fruits
Bananas: As a general rule they're more for show than useful. Bananas can be abrasive if inserted anywhere, and most aren't really round--I'm sure you can find a better substitute. Bananas are much better for visual foreplay, and I don't think I need to explain why.
Pineapple Ring: I'd feel remiss if I didn't at least mention these--they're fun, they can be put around nipples for kicks. If you have some rings lying around, by all means play with them. I would suggest even eating them but other than that don't lose sleep trying to get this one into your sexual repertoire, or anything else for that matter.
Strawberries/mango/cherries: Now these are some fruits you can really use. Any of these can be dipped in chocolate and fed to each partner. Cherries are fun to play with when you have whipped cream around, and strawberries are a nice alternative to finger-painting when you have condiments out to play with--think paintbrush for chocolate.
Keep in mind that all fruit comes with the same sugar warning as before -- don't play hide-and-go-seek with it, or both partners will regret it later.
Veggies
As a general rule, college students don't eat vegetables, so it's probably unlikely that you have a cucumber lying around your room. But that doesn't mean vegetarians can't have their fun. Good items are things like cucumbers and Japanese eggplant. Bad ones are Jalapenos. What do cucumbers and Japanese eggplant have in common? They're smooth, round and non-abrasive. These are veggies that you could use without a condom over them. Anything else really is going to be to abrasive to sensitive tissue and do more damage than fun. As for the Jalapeno, anything spicy to your tongue should not move south of it.
Dairy
I'm not really sure why anyone would use this, but dairy follows a simple rule: Don't use it internally. The only possibility I can think of is if you used plain yogurt (no fruit and no flavor--not even that vanilla one) and you want to use a live culture one (that would be the friendly bacteria). If you're dying to know more, I'm sure a biology professor running around campus would be more than happy to discuss it.
Meat
Playing hide the salami, using your beef bayonet or riding the bologna pony--meat euphemisms have given us a world of expression to describe penises and sex, so at some point I know it's crossed a lot of people's minds to use the real thing. Please resist the temptation, or at least practice safe meat habits. Yes, that means cover it with a condom. The nitrites used to preserve meats aren't good for anything but digestion.
Candy/Dessert
Pop Rocks: Good when used alone but great when shared with a friend. Just put some in your mouth before kissing someone, and it'll give them an unexpected kick. There's something about using childhood foods that's just entertaining.
Chocolate: Beside the great endorphin kick chocolate gives to any evening/morning/afternoon, it also makes great body paint. If you're in control, tease your partner by putting it anywhere and licking it off, just make sure you avoid any place they're just dying for you to go--for at least a little while. Another idea is to give your partner the sauce and let them draw a tasty map--and who says you can't follow directions?
Also, chocolate is a great food to warm up when playing with hot and cold. Watch out though--it's easy to overheat, so test it out before using it on some unsuspecting accomplice.
Also to guys, why not try creating your own candy bar? You'll be surprised how many girls who might not be down for oral action suddenly take interest in giving Hershey some business.
Cake-Icing Tubes: Getting a sugar high never tasted so good. I separated these from chocolate mainly because they don't have the same chemical kick but you can use most of the same tricks. While you should use chocolate for reliving your finger painting days, use these more precise "tools" for writing suggestions, desires, directions, or other random thoughts you feel like jotting down. Write on backs, legs, chests -- you get the idea--but what's fun is to write on someone where they can't see it and have them guess (then act out) what's written--just a fun twist on an old game.
Popsicle: Definitely not just for kids. Along with using this to cool your mouth down before oral exploration, it also comes in as a pretty hand drawing tool. Using one of these to trace around your partner's body, inner thigh, back of their knees, chest, anywhere they have nerves to tingle. Afterwards you might want to lick up your mess, and together the mix of sensation will be amazing.