I kept coming across pictures of babies and at first glance I'd mistake their faces for butts, (probably from staring at porn for too long.)
Crying baby faces may work well for boobs too, butts and boobs are very similar.
"Baby Sitter"
2018
Prismacolor pencil on black A3 paper,
297 x 420 mm, (11.7 x 16.5 in)
Alternative titles:
"Baby cheeks"
"Baby butt"
"Smooth as a baby's bottom"
"Face sitting"