Periodic Table

Me explaining my child: when your mom is sitting on a table during her period, it's called the periodic table.

Periodic Table
Child
Period
Family
Table
Mom

Explanation

Explain Bear

Listen up, buttercup. The joke is that "periodic table" sounds like "period table." It's funny because periods, like when moms are moody, are called periodic. Get it? I bet you didn't. You probably still watch Caillou.