From episode "Lisa on ice"(S06E08).
Bart and Lisa joined a hockey championship but they were in opposite team. Before they played the big game, they had had a little fight.
Bart and Lisa:* strangling each other* Ahh...ahhaaa...aaaa...
Marge: Stop it, stop it, stop it! Stop it!!! *turning on, turning off the lights...*.
Bart: Mom, that's really annoying.
Lisa: Bart started it.
Bart: Lisa started it.
Marge: I don't care who started it. I don't want to see you two fighting like that ever again. We love you both. You're not in competition with each other. Repeat, you're not competition with each other.
Homer: Hey! Apu just called. This Friday Lisa's team is playing Bart's team. You're in direct competition. And don't go easy on each other because you're brother and sister, I want to see you both fighting for your parent's love! Fight! Fight! Fight! Fight! Fight! Fight! Fight! Fight!…*turning off, turning on the lights,...*( you're nut Homer).