Because male dogs have a knot at the base of their penis. The male sticks it in when he splooges,to keep it all in and increase the chances of pregnancy. And they're stuck together like that for a few hours.
Not only that captain Jack and @rosalinas. They have a literal boner. They have a bone in their wiener. I believe it has peculiar name. Sometimes it gets stuck.
It's called an os penis, and humans don't have it. Makes it impossible for male dogs and cats to pass bladder stones and they can actually die fairly quickly as a result.
You people are so retarded. I can't believe you're allowed to have internet at all. It' takes literally a second to browse penis captivus and learn eeeevrrything about it, but you people are so motherfucking lazy and full of yourself, you think you know it all, you'd rather just be a smart asses and tell someone he's the one who's stupid. Arrogant idiots.
He's jealous because apparently he lives in a third world country but we live in first world countries. We can't complain about anything or be ignorant to anything around him.
He suffers from ZeroBall Syndrome, and I hereby prescribe Growacet. http://cdn.lifeinthefastlane.com/wp-content/uploads/2010/02/growacet-bp.jpg
He criticized me because I had to read a book called Touching Spirit Bear for required reading and he had to read a book about child abuse or something like that and he said he hated me because of it.
Why do dogs butts stick together after they do the do...
Jk jk.
He can join if he adjusts his attitude,maybe learn about anatomy a bit more.
He suffers from ZeroBall Syndrome, and I hereby prescribe Growacet. http://cdn.lifeinthefastlane.com/wp-content/uploads/2010/02/growacet-bp.jpg
(I'm being sarcastic)