Guys, What do you feel when you have a crush?

I know it's a really vague question, but I wanna know more about how men feel when they start liking a girl.
Do you think about her during the day?
Do you wait for her when she's near hoping that she would approach you?
Do you tease her (nicely)? Do you like being tease by her?
Do you feel nervous when you know you're gonna see her?
Do you play games? (Being hot/cold) When you're cold do you secretly expect her to notice that and maybe have her attention?
Guys, What do you feel when you have a crush?
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