Smaller bum?

"I wish I had a smaller bum" my wife grumbled. "Do you wish I had a smaller bum?"

I peered over the top of the paper. "No, not really" I told her.

"Aww, you're sweet" she gushed. "Is it because you love my bum the way it is?"

"No, not really" I replied.

Spoiler:

"It's because it'd look bl**dy ridiculous with legs that size attached to it".