To get blessed or screwed in Riot's videogame Teamfight Tactics. The verb is derived from the name of Riot employee and TFT design director called Mortdog.
Very prominent element of the video game is randomness. However, players like to pretend that Mortdog is responsible for everything that happened.
This catchphrase is getting out of hand and players and streamers are using it outside TFT to describe anything (un)lucky that happens in their lives.
Ex 1:
Streamer 1: *has three 4-costs*
Streamer 1: *gets Recombobulator augment on 3-2*
Streamer 1: "holy shit I got mortdogged"
Soju: I went 8th again...
When someone botches something so completely and terribly, that it can only be compared to Heidi Montag's abysmally poorly lip synced, poorly danced, total failure of a Britney rip off performance at the 2009 Miss Universe pageant.