Let me perch for the stale jokes.

what's the difference between your mom and a washing machine? the last time i dropped a load in the washer it didn't follow me around for a week

Your mum so fat that when she steps on the scales, her telephone number comes up.

your mama is so fat that she doesn't need the internet she already is world wide

or..

Your mama is so fat that even Dora couldn't explore her

Did you had to google it, too?

your mama is like a bowling ball she gets picked up, fingered, thrown in the gutter and still comes back for more