Slipping people acid is NOT COOL! It happened to Mark Hoppus and he told Red Bull TV the story about the time he was given LSD and it hit right at the start of a show. Things didn't go well that night... (Skip to 1:40 and hear the story from Mark at Lollapalooza.)
And just to make sure we're clear, this wasn't Mark bailing out on a Blink-182 show. He corrected Alternative Press on that a few minutes ago.