Yo mama so fat she has gravitational pull (laughs). 

Yo mama so old, her wrinkles have wrinkles. 

Context:

The informant is a college student explaining jokes that they know, bringing up a particular type of joke they would frequently do with their brother.  

Personal Thoughts:

This joke is an interesting piece of folklore as it is a part of a specific genre of jokes that have become very popular in folk communities, particularly Gen Z folk communities. While the jokes are typically short, they follow the same structure, using an insult as a way to be humorous. From this, one can also gather that there is particular importance placed on the mother, and by insulting one’s mother, that is a worse thing to do than insulting the recipient of the joke. Thus, by having this specific structure of joke, it is able to continue on in new ways, as people repeat the joke with new insults, allowing for multiplicity and variation.