Yes, twice so far.
One time I was 8 months pregnant and I was laying on my back ready to receive oral. My hubby was just diving down and he actually dived on the bed, it made me giggle and I farted within inches of his face. That was hilarious.
The last time we were laying crotch to crotch but I was using toys. After we had just got done with anal sex and it was a good pounding. If squirted all over him and farted at the same time.