I've been watching the Amazing World of Gumball (one of the best shows I've ever seen) lately, and I've found there are only a couple sneezes so far. Here are the ones I've found so far:
1. The Date (from either Gumball or Richard [I don't remember], I think the sneeze is between the beginning and middle points)
2. The Microwave (from Gumball, the sneeze is around the start)
I haven't seen either of these episodes, but I do know that both have sneezing in them. I also don't know if there are any new episodes with sneezing, but I hope there are.