A fish out of water.

This idiom is easy to understand because we all know that fish live in water. They don’t hang out in bars, so this fish is definitely out of its familiar environment (water) and it’s communicating how awkward, or strange it feels. 

However it looks like the fish is resigned to stay in its new environment (the bar). We know this because it says, 'what the heck' which is a term of resignation in the sense of acceptance. 

If you feel like a fish out of water, you feel awkward because you are not familiar with your situation or surroundings or feel different from the others in the situation or environment. 

Here's an example of this idiom in a conversation: 

So, how do you like New York so far?
It's great, although ...
What?
I don't know. I'm a bit of a fish out of water here.
That's just because everything is so new.
True. It's very different from my home town. 
You'll settle in soon.
Thanks. I hope so.