In the mid to late 90s, a Snap was a certain type of insult told in a specific format..."Yo mama" jokes,
basically, which would often result in the phrase "Oh SNAP!" being yelled out when a given insult hit
particularly hard.
For example...
"
Yo mama so fat, when she tried to weight herself,
the scale said “one at a time please.”
"Yo mama so old, she remembers when
the Grand Canyon was just a ditch!"
"You're so dumb, you sold you house for rent money" "...Oh, SNAP!"