Most likely an outgoing, crazy, witty person. Watch out for these ones, Its like getting a curve ball at the end of a baseball game where the only pitches being thrown are straight down the plate! Other discribing adjectives
Origin in English/Australiancricket vernacular, drinking sessions at pubs can be scored using cricket scoring format of wickets/runs (Aus) or runs/wickets (Eng), where runs are drinks, and having to urinate is a wicket.
You might tell your mates as you stand up that you just lost another wicket.