1. verb, slang To suddenly express anger or excitement in a very visible way. Mom will freak out when she finds out we broke her vase! I totally freaked out when I heard we'd won tickets to the concert.

2. verb, slang To startle or frighten someone. In this usage, a noun or pronoun can be used between "freak" and "out." The sight of that huge needle completely freaked me out.

3. verb, slang To experience jarring and frightening side effects (such as hallucinations) due to drug use. In this usage, a noun or pronoun can be used between "freak" and "out." I swore off drugs because my last trip freaked me out so bad.

4. noun, slang A bad experience while taking some mind-altering drug. In this usage, the phrase is often hyphenated or written as one word. I swore off drugs after my last freak-out.

5. noun, slang A wild party. In this usage, the phrase is often hyphenated or written as one word. Someone in our class always throws a real freak-out at the end of the school year.