To pull ones underpants up too quickly, thus causing the testicles to emerge either side of the gusset.
"Bloody hell, I was getting changed so quickly that when I pulled my kegs up, it was like looking at a pair of flies eyes".
by Giles Bradley April 24, 2005
Get the flies eyesmug. by Dunnomatw June 11, 2022
Get the Flies on your eyesmug.