"Curious" is the 7th episode in Season 2 in Angry Kid.
The family are eating breakfast in the morning. Angry Kid wondered what was happening last night. He claimed that he got up in the middle of the night to go to the bathroom when he could hear strange noises coming from his parents' bedroom. He got confused because his mother seemed to be in both extreme pain and was begging for more, but Dad reckons that he was just dreaming. After Angry Kid asks what a "butt plug" is, Dad tries (and fails) to distract him by suggesting to go see a movie. Angry Kid, still not having had his curiosity satisfied, calls Sandra for details about the situation, which is when Dad immediately offers him five pounds never to speak of it again. Angry Kid accepts, but only if the amount is changed to ten pounds. After that, he asks how much a butt plug is.