Mona Lisa smile 

A person (usually girl) who are shy and have a small subtle smile.

But the smile is the sweetest thing ever and lights up the room

Person : subtle smile
S/0 :wow I’m just obsessed with you and your Mona Lisa smile

Mona Lisa smile by Idontreallyknow555 May 1, 2022

Mona Lisa Smile 

That look on a girls face when you cum on her tits. Not a full on grin, but just a subtle smile that you aren't sure what it means, but you think she's enjoying it.

Sherry gave me her Mona Lisa Smile when I came all over her tits, but it went away after my buddy Tim nutted all over her face.

Mona Lisa Smile by Ed Rooney Jr July 18, 2016

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.

"Wow, Sam's lips look really shiny," Friend 1.
Friend 2, "Yeah, I just gave her a Mona Lisa Smile."

Mona Lisa Smile by The Drs September 2, 2010