i just thought these up... feel free to add more.
yo momma is so old that she remembers when jesus invisibly returned
yo momma is so lazy she auxilliary pioneered one month and didn't even meet the national average
yo momma is so fat, she was the reason why the society stopped serving food at the conventions
yo momma is so dumb, she thought Awake! could be used as an alarm clock
yo momma is so dumb, i asked her to do some RV's and she got an STD from a mobile home
yo momma is so ugly, they make her put something on her head even when she's not saying a prayer in front of unbaptized male publishers