To send someone a link to 80s pop star Rick Astley's "Never Gonna Give You Up" video, making them believe that they're gonna see something completely different. The meme originated in 4chan's /v/ (videogame) board, when the official "Grand Theft Auto: San Andreas" trailer was coming out on the game's website but couldn't be watched due to heavy traffic. Playing a prank on everyone who was reading, an anonymous 4chaner said that the trailer was on YouTube and posted a link to Astley's song. Since then, the Rick Roll has been made countless times, not only on 4chan but on the whole of the Internet.

It’s an acronym standing for Can’t Remember A Fucking Thing. It’s usually used to describe embarrassment at being unable to remember someone (CRAFT moment); going onstage as the lead in the latest theatrical performance and your mind goes completely blank (CRAFT situation); the next morning after a night when you got pissed as a fart and woke up in bed cuddling a traffic cone and a string of fairy lights wound round your prick.

When what you think is a link to something you want to see actually directs you to a video of Rick Astley singing "Never Gonna Give You Up." This is common in the WoW community.

To post a misleading link with a subject that promises to be exciting or interesting, e.g. "World of Starcraft in-game footage!" or "Paris Hilton blows Busta Rhymes' dick" but actually turns out to be the video for Rick Astley's debut single, "Never Gonna Give You Up". A variant on the duckroll. Allegedly hilarious.

an internet phenomenon in which someone provides a link claiming it to be relevant to the topic at hand, only for that link to redirect you to the music video of Rick Astley's "Never Gonna Give You Up."

To be fooled by a mislabeled video link that takes you to an extremely 80s video of Rick Astley.

Swiss rolls so good, that you're never gonna give them up