When a male inserts his penis into an oversized bucket vagina and realises that there is very little hope of getting any "purchase" hence unlikely to bust his nuts. Similar in meaning to throwing a hotdog down a hallway.
Brian: I couldn't believe my luck last night when I finally got to nail Felicity but my luck turned when I went to slip in my sausage and could not feel a thing!
Terry: I heard rumours that Felicity has a large bucket minge, Jeff said it was like a teatowel in a tumble drier