"Flasche" is used in at least one lesson sentence here to mean "loser" (basically an inept, incapable, or incompetent person), but I disapprove. It's a colloquial or slang term that I don't think has any business in introductory German lessons. There's been quite a bit of discussion about this here in the past, and I think I'm in the minority on this point. At any rate, if Duolingo wants to do some special lesson sections devoted to alternative slang meanings, great! But keep it out of the ordinary lesson material. As a new learner, translate this word as "bottle".
As for "wet", I don't see that as a possible alternative, but maybe I'm wrong.