the most basic definition for "getting your tits wet" is something that is ridiculously awesome or something so fun that it is retarded. It is not meant to be sexual or literally meaning to get a wet chest, unless are doing something sexual or you're near water and it is bringing you an unmeasurable amount of joy. Now lets say you are doing something that is annoying and possibly puts you in a bad mood, in this case your tits are dry.
you are making out with a playmate = your are getting your tits wet
you just arrived at Panama City for Spring break = your tits are wet
you just won the lottery = your tits are soaking wet
you got hammered the night before and had sex in the ocean = your tits were wet in more ways than 1
you just got a DUI = your tits are dry