It means he is flirting with you, so do the same back.
Lick your lips and wink and they will tickle you till you die
it dosent really mean anything, does the guy like you? were you just playing around? was it for fun? so it dosent really mean anything, unless you have got something going on!!
if a guy tickles a guy he is gay, if a guy tickles a girl than he likes you.
They do it because; they like to make you laugh, they like to touch you and they like to know that they can inspire a reaction from you.