Repeatdly over multiple maps. Witnesses- Wub and BOB. He did also do it on Murderball when I was there - 10:00 AM CST 10/25/13 on BZ
I also believe he has a speed cheat of somesort as he out ran a scout as a engineer. Interstingly enough he also plays as: f(x,y,z) - the guy that was speeding around as scout on crack with HW gun and sniper rifle a coupel days ago.
#11 "Twitterion" 2006 VALVE_0:4:1456054395 315 42:12 191