Set five enemies on fire in 30 seconds.
actually, you can do flamethrower with 2 people.
just go to 2fort, have the phat gettin pyro in the sewer tube facing outside.
the other guy stands on the edge of the pipe and when he gets ingited, quickly step back and submerge himself and get back into shallow water of the pipe. rinse and repeat 5 times. I suggest using a heavy as the torch so you ensure enough health not to die if you arent quick enough putin out the fire 5 times.
since you put yourself out apparently it counts as a new and seperate torching.