Balloons, Breasts and Weddings

I was reading a book about writing exercises when I came across a line that I didn't really know how to react to.

"Her breasts balloon; the sky opens inside them"

It wasn't a terrible line until I learnt who wrote it- the daughter. The daughter was writing about her mum's ballooning breasts???

This was the exercise:

I mean, am I the only one who finds this really weird/odd/creepy???