If you dont know what tattoo you wanna get, then dont get a tattoo. Dont let your friends pressure you into getting one.
Remember bro, that ink is gonna be on your body for the rest of your life. Unless you decide to get it removed with lazorz, which is a pretty expensive and painful procedure iirc.
Id say wait till you have the money to get the one you *really* want.
edit: But if you are really really determined to get one, POLAR BEAR