a lone wolf
A lone wolf is someone who goes to a bar by themselves, just so they can get drunk and look cool, even though they're probably just going to be picked on by some random cougar.
He went to the bar alone. No friends. No drinks. Just a sad man who looked cool for about 10 seconds.
She walked into the bar by herself. She ordered a drink and immediately got hit on by a man who looked like he just escaped from a zoo.
He went to the bar because he had nothing better to do. Now he's just sitting there with a drink and a broken heart.