Two gay guys
 

There are two gay guys having sex. Suddenly, the phone rings, and with an exasperated sigh, one gets up to answer it.

Before he leaves the room, he looks at his lover and says "No masturbating until I get back!"

After a few minutes, he returns to see sperm all over the wall and his lover lying on the bed, smiling sheepishly. "I thought I told you not to masturbate!" growls Gay Guy #1.

"I didn't masturbate," he says, "I farted."