>“I Herd U Liek Mudkips” is a catchphrase that became popular through its frequent usage on 4chan in the mid-2000s. Variations on the spelling and the addition of “so” to the beginning of the phrase can also be found. Although its meanings are obscure, the phrase is commonly used as an identifier amongst 4chan users outside of the imageboard community, similar to the usage of “The Narwhal Bacons at Midnight” on Reddit.
>Mudkip is a blue and orange water-type Pokemon character who first appeared in the Ruby and Sapphire games, released in the US in March 2003. The phrase “so I herd you like mudkips” originated in early 2005 with the deviantArt group MudKipClub. The account was founded on October 5th, 2004 as a place for users to share Pokemon fanart. The club was not limited to Mudkips, however, as the first artwork depicted the character’s final evolution, Swampert. The owner of the community began posting the phrase “so I herd you like mudkips” on other users’ comment walls as early as February 7th, 2005. While the motive behind the comments are unclear, the wall messages served as an invitation to join the MudKipClub community.
Source: Know Your Meme.