Mona Lisa Smile
After you cum you take the residual cum on the tip of your penis and apply it like lipstick to your partner's lips.
Example:
"Wow, Sam's lips look really shiny," Friend 1.
Friend 2, "Yeah, I just gave her a Mona Lisa Smile."
"Wow, Sam's lips look really shiny," Friend 1.
Friend 2, "Yeah, I just gave her a Mona Lisa Smile."