A guy that would rather have anal sex with his girl instead of penetrating her vagina. Butt wranglers are often former prison inmates, are closely related to former prison inmates, or are gay guys who have yet to figure out that they are gay.
That butt wrangler had the town's most fuckable girl until she got rid of him after he ripped her anal cavity from all the poop chute love that he would insist upon.
On a long haired dog, cat, or sometimes, an unwashed co-worker, a combination of a loose bowel movement stuck in the hair around the butt. This mass has been sat upon, flattening it to a waffle-like appearance. In a co-worker, the presence of a butt waffle is indicated by a strong smell of "old shit".
"Hold still, you fucking cocksucker. If we don't get this butt waffle off yer ass, you'll have to stay outside for a week." (Generally screamed at a dog or cat, Not a co-worker.)