ATAST!! 

... means, And Then Apple Sued Them! Exclamation points follow the acronym to emphasize the fact that any possible thing that has happened, is happening, or is going to happen will probably be followed by an Apple law suit against any person, company, nation, group, plant, animal, natural resource and/or toddler attempting anything.

me: Hey. Look. A rectangle.
my friend: ATAST!!
me: Wha?
my friend: Oh, you didn't know? Apple doesn't allow other people to make rectangles. Or ____ (fill in the blank with any other thing that has ever been invented).

ATAST!! by JGuy The Great! April 12, 2012

ATST 

At the same time.

"Sam and I said hi ATST"

"I want to, but i don't ATST"

ATST by AtTheSameTime October 22, 2009

Atas 

In Singlish, atas means "high class" - the word is derived fromt he malay word meaning "upstairs"

I don't like to go to all those atas places; surely spend money like siao!

All his friends damn atas one, you think they will go to that sort of low class place to eat?

Atas by jschnorng October 21, 2006

avast 

hold and desist

Avast ye scurvy scoundrels! (Will you vitamin C deficient gentlemen please stop what you are doing.)

avast by Anonymous August 1, 2003

avast 

A term commonly used by pirates and pirate wannabes. Means cease and desist.

Arr, avast lest ye want yer captain te chop off ye balls!

avast by Mark November 29, 2004

Avast 

A free antivirus program that i use, developed by Czech computer technology that tends to update your virus database very often, and tell you about it pretty much daily and can get a little annoying, though it is a decent program that works and is free.

Avast! virus database has been updated!

Avast by NoReward October 16, 2011

atst 

At the same time

You see I'm not a woman, I can't do that atst

atst by Lazerdude May 6, 2011