Basically popular guy seme hid his phone on the nerdy ukes underwear so he doesn’t get it confiscated by the teacher (yeah it really turned out this way even tho it’s not one I’ve seen in a Yaoi story before…). However the phone keeps vibrating leaving the uke feeling aroused, embarrassed and goes to the bathroom. Seme follows and the history is already making for the pair of them.
Now I will never look at phones the same way again…