Coning isn't a great prank anyway.
For those who aren't familiar with the “coning” prank which has gone semi-viral, it is where you get an ice cream cone from a drive through and grab it from the ice cream instead of the cone when it's handed to you. The idea is to film the employee's reaction to the weird thing you're doing, but it seems more like you're playing a prank on yourself, and also how you get ants. But those employees have seen YouTube as well, and there's always the chance they'll know they're being pranked.
That's what happens in this video, where an employee refuses to play along with the prank. Can't say we blame the guy.