Dangling Seabiscuit
When your penis drops down after emerging from a vagina or other crevasse after you go to town on her (or him if you're into that).

The joyful feeling after you've cum and your penis can finally rest, whilst still being fully erect like a racing horse.
"I pummeled her so hard that my dangling seabiscuit lasted over 30 minutes."

"That girl Nicole gave me a weak dangling seabiscuit last night."