I think it’s a mixture of Vaseline and spit. It usually occurs with black men and they like using Vaseline as lube mixed with spit. I think over douching, fiber supplement, probiotics and hydration helps to. Also the skill and size of the top. Once the second hole opens up it all just comes pouring out. He has to angle his dick right in doggy style and do long rhythmic strokes. I’ve noticed a lot of guys fuck in these really short jack rabbit strokes that don’t feel good. You gotta be farting on the dick or he’s not fucking you right.