Senpai! Waza to ja Nai n desu! - Vol. 2 Ch. 27 - Extra Classes!

[MangaDex]

 

[marszymek]

It reminded me of this one guy in primary school who didn't notice he had boner and stood up. I don't remember if teacher was looking at him but class did

 

[Darkmetal014]

Life saving tip: tense your arm or leg for about a minute to get rid of unwanted boners

 

[Dorraj]

God this is an actual nightmare. Random boners are the bane of any teen boy's existence