YDMT

Short for 'you don't mean that'. Often they do mean that, it's just denying it.

Close friend 1:"No offence but I honestly can't handle being around you any longer"
Close friend 2:"YDMT, do you?"

Uno Mas

Spanish for 'One More'. It is popularly used in drinking games, and is also used as a phrase when playing certain video games, such as Mario Maker.

'That was a great game, but honestly I should get some sleep' - Person 1
'Uno Mas!' - Person 2

Subwoofer

Though it can be referring to a component of a loudspeaker, subwoofer also refers to/means puppy (with woofer referring to dog) in DoggoLingo.

Person 1: Aww look at that woofer and its little subwoofers!