I am very new to the forums but ive come across this problem already. My fermentation was strong enough to completely blow my airlock off my carboy leaving it exposed for almost a whole day and it came out great. So i dont think you have to worry about contamination or throwing your batch out. Best advice i got was a blowoff tube. Replace your airlock with a short length of extra vinyl tubing place one end in the stopper and the other into a bowl or other vessel filled halfway with water and sanitizer that way any blowoff will go safely into your bowl. No fuss no muss.