When a girl on xbox live hears a guy talking over a mic and says to him "OMG you sound sooo HOT!!!" and immediately invites him to private chat(video chat if available) and adds him to her friends list. From then on she either always follows him from game to game or invites him to her games just to hear his voice, which turns her on - thus becoming "Wet in the Pants".
Essentially the female equivalent of "Tight in the Pants"
Tori and Kelsey are always bugging FDD to join their games and having him say things just to hear him say them because they are so Wet in the pants over the poor guy