I knew a guy (dead now) who used to do that, so I was told. He would do it to his friends when they left their drink or beer unattended cuz he apparently thought it was funny. He said it would give them the "fudge puddles." That was the only time I ever heard of that. Apparently it can be life-threatening, which ain't so funny. Of course, anybody putting ANYTHING in someone's drink can be life-threatening for the guy who does it too, if he gets caught.