Lipstick Stain

You use this term when you think someone is cheating {Preferably a female.}

It's also used as another term for oral sex. {Preferred for females.}

"You're a lipstick stain."

or

"I stained the lipstick last night."

Muh

Slang from Wales: When you think someone is lying you'd use it to show that you know/think they're lying. Also this is used with a gesture where you brush your hand up from the neck to the tip of the chin.

Muh, you didn't do that.

Gnomeo

A gnome from a remake of the classic, 'Romeo and Juilet.' but inserting the pun of Gnomeo, remaking the film but as gnomes.
You call someone a Gnomeo, they're a Casanova and a main protagonist in real life.

"Damn Gnomeo is really cute."