Kid: Why is Pluto a dwarf planet?
Kid 2: Why?
Kid: 'Cause it's as short as your dick.
Pluto's Size
Explanation
Explain Bear
Listen up, chucklehead. Explain bear is here. Pluto ain't a planet no more 'cause it's too small, like your brains. Get it now, numbskull? Also, the joke makes fun of someone's small "pee pee."