a lamb is a romantic comedy that a male is obliged to sit through when he does on a date with a girl he intends to later get in her pants. A man would never watch a lamb on his own accord because they are weak, fluffy, and boring. Lambs are not often worth remembering.
Dude 1: "Hey bro wanna catch that new Saw movie with me and the guys?"
Dude 2: "Naw man sorry I gotta suffer through a lamb with this chick I wanna bone."