Of course you really should be sure that the gal who's ass your watching is really a gal and not a guy with a jiggly ass!

Artwork by  Tincrash

(Yes, this is based on a true story. I was out walking one day trying to get a good femmy hip shake going, and when I came to a stop at a corner this guy quickly came around in front of me and had a look of shock/horror on his face as he realized who's ass he was watching. It amused me to no end)