1 definition by Lord Derpington of DerpMoar

Do Not Shag. A an obscure yet fundamental branch of man law usually enforced by friends and other people that have your back.

There are 2 levels of DNS:

Catagory 1: The most common application. Do not sleep with the aforementioned unless drunk and intoxicated, which gives you a ready-made excuse if your friends call you out.

Catagory 2: Indefinite. Any kind of sexual encounter with this person is heavily frowned upon, and is likely to result in ridicule. Designed to stop you from sleeping with a heffer or duff when you're lashed and feeling horny. A person may also be a catagory 2 if sleeping with him/her would cause waay to many problems/trouble, e.g. your best friends boyfriend/girlfriend.
Tom: "I heard becky is coming to the party tonight."

Josh: "As long as you're careful bro, she's a cat. 1 DNS. She only looks good after half a bottle of vod".

Tom: "Don't worry about me dude, i've got this!"

Josh: "Haha, it's all you man."
by Lord Derpington of DerpMoar August 8, 2010
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