What does a guy's face expression look like when he is turned on or has a boner?

[Anonymous]

is there a common face gesture or feature that reveals a guy is turned on by seeing a girl or even perhaps has an erection? the guy I like seemed pretty happy to see me last week, he had sort of a surprised face to see me out of nowhere, and then a smile and jaws open...and eyes wide...he seemed pretty enlightened to see me...was he turned on by the way I was looking and smiling back at him? can he also pretend to play it cool and have a neutral face, trying not to smile as he has a boner? may be bite his lip or press his lips as if he's about to laugh...

[Anonymous]

there is no common expression. he might look really turned on or have an "oh crap" look. more than likely though, his expression won't change.

[Asker]

Wait can you describe what an 'oh crap' look is like lol

[Anonymous]

no, sorry.

If he's a big guy, everyone around is going to know. If he isn't a big guy, you just have to wonder.