If you lie down with dogs, you wake up with fleas.

Internet meme (/ˈmiːm/ meem) is an activity, concept, catchphrase or piece of media which spreads, often as mimicry, from person to person via the Internet.[1] Some notable examples include posting a photo of people lying down in public places (called "planking" and uploading a short video of people dancing to the Harlem Shake.

A meme is "an idea, behavior, or style that spreads from person to person within a culture".[2] An Internet meme may take the form of an image, hyperlink, video, website, or hashtag. It may be just a word or phrase, including an intentional misspelling. These small movements tend to spread from person to person via social networks, blogs, direct email, or news sources. They may relate to various existing Internet cultures or subcultures, often created or spread on various websites, or by Usenet boards and other such early-internet communications facilities. Fads and sensations tend to grow rapidly on the Internet, because the instant communication facilitates word-of-mouth transmission.