The effect noticed when sleep-deprived friends spend enough time together that nearly everything becomes funny. Mundane, everyday, happenings become ridiculously hilarious, and normally funny jokes become so hysterically laugh-out-loud funny, you'll be in danger of dying from asphyxiation. Named because the SNES game "Lemmings" quickens the onset of the Lemmings Effect.
"What're those two laughing so hard about?"
"I think one of them dropped her pen. That's the Lemmings Effect for you."