When I was young, we used to have a rented hall that was pretty old. In the summer, they'd open the windows to let some air in and as it went dark outside (Thu meeting) the daddy-long-leg crane flies would be drawn to the light and start buzzing around the ceiling (quite high / domed), sometimes venturing down.
Obviously, no one wanted one of those things flying in their face so you kept half an eye on where they were.
My sister (2 years older than me) and her friend were sat in the row in front of me one evening and as the prayer droned on and you heard the buzzing of the flies, I saw they were keeping an eye out for them too.
So I reached forward and flicked their hair behind their ears.
OMG, I never thought anyone would scream THAT loud! And of course the surprise of them screaming made others jump and half-shout out too.
I think the payer finished and I remember being pretty grateful that no one knew it was really me and not an actual fly. I think I would have been in serious trouble.