"You think you're going to date my sister? As if." The phrase is a dismissal. It means "that is not going to happen" or "I don't believe you." The tone is sarcastic, often accompanied by an eye roll. It became a cultural catchphrase in the 1990s, thanks to the movie Clueless. Cher Horowitz said it with a sneer. A generation copied her.

The phrase is not new. It has been used in English since at least the 1800s, but the modern sarcastic use is American. It can be playful or cutting. Between friends, it is a joke. Between rivals, it is a slap. The two words are short and sharp. They end a conversation without explanation.

Similar dismissals

• Yeah, right: sarcastic agreement.
• Whatever: bored dismissal.
• Dream on: mocking hope.
• Not happening: blunt refusal.

"As if" can also be used literally. "It looks as if it will rain." In that case, it is neutral. The sarcastic version depends on tone. In text, it is often written with an exclamation point or a period. "As if." The period makes it final.