When I saw the clouds last week with my daughter she said "butt cheek clouds". When my adult friends saw the clouds on July 4th, they compared them to just about every "private part" found on the human body. Well, it turns out these clouds are named after a part of the body.

The bumpy looking clouds are part of a severe weather system and are called Mammatus clouds. Yes, like "mammary" or "a breast".

According to Wikipedia

Mammatus, meaning "mammary cloud", is a cellular pattern of pouches hanging underneath the base of a cloud, typically cumulonimbus rainclouds, although they may be attached to other classes of parent clouds. The name mammatus is derived from the Latin mamma.