Hangliding on a friday refers to the superstition
that it is bad luck to hang glide on a friday. The superstition originated thanks to the mass hangliding tragedy of 1972, where 18 hang gliders lost control of their instruments in Lancashire, England as gale force winds ruthlessly sent them flying around in dangerous circles. 7 people died and the weather had been fine the whole month apart from that day, the previous friday and the following friday.
"I'm going hang gliding with my fiance on friday"
"WHOAH WHOAH WHOAH, you don't wanna be doing that, remember the mass hangliding tragedy of 1972! You should never go hangliding on a friday!"