Source of picture: Teasing Video, Cock Teasing - Indecisive Captions
SLAP THAT SPURT
This is an example of a cuckold where his wife use his nuts to moderate his excitement.
She can back him off from his excitement by flicking a testicle or giving him an open-handed slap, but for some, that testicle abuse just pushes him over the edge
For easily excitable cuckolds, draining them once manually can sometimes be useful before allowing him to watch his wife’s coupling with her lover.
One final note: look at the power of that spurt - guaranteed that it landed on his face!