Bukkagay describes when men are participating in a bukkake, but there are too many of these men (mabey around 15). Since there is only one female, the men must squeeze their hips together to form a tight circle around her. Thus, each man is essentially touching asses with men on either side of him, and some of them wonder if the situation is worth it at all.
"Dude, last night I was in a bukkagay with 12 of my buddies, and we had this really hot chick come over!"
"Um, you're gay."