The feud between Jimmy Kimmel and Matt Damon began in 2003 during a live TV show.
Jimmy fired an improvised joke at Matt and apologized for running out of time for him on the show.
Matt responded by making a video with Jimmy's then-girlfriend, Sarah Silverman.
The feud escalated with each celebrity pranking the other on their respective shows.
The rivalry continued with appearances at award shows and humorous social media exchanges.