Do you really think that it's just because he likes him that he's tickling the OP's feet? There are other reasons (such as not to present himself as overly aggressive) that the aggressor's just tickling the OP's feet. If I'm correct in reading OP's post, he's usually studying with his aggressor, his friend, and his girlfriend. What better way to show your superiority without being overly aggressive in a thinly disgused game of feet-tickling. Not only does the aggressor show that he can physically and mentally (in the form of making the op laugh through tickling) overpower the op, it sends a subconscious message to people around him, including his girlfriend, that the OP is a chump.
> They are a lot older than that; too old for that.
Any notion of maturity was dismissed the moment the OP referred to himself as a boy.