I. e. a knotted cock will get stuck in a hole when sufficiently excited and inserted deep enough.
Staying there unless forcefully removed with a sharp tug, expelled by a very unhappy partner, or the excitement level falls low enough that the knotted cock can freely slip out.
A tied knot should give (extra?) stimulation when tugged outward (but not free), and possibly act as a hindrance (but not completely, if implemented) to cum spray.
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