Kangaskhan and Nidoqueen are from Nintendo's Pokemon and this screenshot's taken from Valve's Garry's Mod.

These female Pokemon challenged each other to their contest to see who's belly is the mightiest by inflating them huge. Nidoqueen would say "I still got more power than you, sweetie." and Kangashkan is like "We'll see about that, dear."
You're welcome to think about how they inflate themselves with certain moves, guys, like Blizzard, Water Pulse, stuff like these.