Can be used as a question, answer, statement, or even rarely as an adverb. Again, usage and meaning depends entirely on context. See examples below with associated definitions below:
1. In its most common context, the phrase is used as a general greeting. It is posed as a question to a friend in reference to whether or not he/she is available to go out on a given night.
2. However, it can also be used when a group of friends is already out. In this situation, the phrase can be very confusing for novice users, for, if one's already out, why would you ask if you were going out tonight? It seems repetitive. Yet in this situation, the phrase refers to whether or not alcohol will be consumed by the party in question.
3. In yet another context, the phrase can be used as a subtle pickup line. If used properly, it has a very high success rate. However, it's growing popularity in recent years stems from its ambiguity and so-called 'plausible deniability'. For, even with poor results, a user can always deny any wrongdoing.
4. A fourth usage is used as a general statement professing sincere apology, tolerance and goodwill. Alcohol, again, is usually involved.
5. Finally, an extremely rare fifth version of the phrase has been discovered in just the past year or so. There is much debate over the meaning of this usage, and no one really knows when it can and cannot be dropped. Most logically, one would believe it should refer to an attitude of indifference towards the night; in other words, if something big is going on, then maybe it's worth going out, if not, then not. However, this usage is used very random situations, and its real meaning cannot be ascertained.
"No I can't. I have a huge exam tomorrow."
2. "You tryin to hang out tonight, or what??"
"Yeah dude, beer me."
3. "You look riDICulous tonight. Are you ... tryin to hang out later or what?"
"You mean go upstairs with you?? Steve, you have a girlfriend!!"
"What are you TALKING about, I wanted to know if you were drinking tonight, Jesus."
4. "What the F is your deal, dude?!"
"Yo chill out, man. I'm just tryin to hang out."
5. "Are you tryin to hang out tonight?"
"I'm not... NOT tryin to hang out."