How do I ask a guy out ?

Be straight forward. Make eye contact, tell him you would like to get to know him better and ask him for (Whatever) with you. It works.

Just step up and say hello.
Introduce yourself and pay them a compliment.
"Nice jacket. Love the hairstyle ! Great colours, really suit you !" etc.
That way you've been bold enough to approach. Been polite enough to compliment. And here he is with a babe in front of him paying him complements !
If he's smart, he'll take the bait and introduce himself !

Get your coat big boy you have just pulled.

"Hey hunk, I've been watching you and I want more up close and personal! When and where?"

AND not get laughed at ???.....gonna take some serious work girl...

walk up and say "wana go out" I know its unusual but it just might work

Ask him if he wants to hangout or something?

"Hey, wanna get a coffee?"

Hey do you wanna hang out some time?

it's simple. you just ask.