It recently became known that The International Dota 2 champion Stanislav «Malr1ne» Potorak from Team Falcons received a VAC ban.
His teammate Ammar «ATF» Assaf commented on the incident (in a joking manner):
We have some content for you from Malr1ne. See? He got a VAC ban — cheater, smurf […] He always cheats — that's how he won TI […] today we exposed him
Malr1ne expressed himself succinctly:
Guys, it's GG [Good Game]. I don't know what we're going to do about this
A VAC ban is usually issued for cheats, the use of third-party software, or smurfing (when experienced gamers play on other "simple" accounts).