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The scene quickly became a favorite among Mass Effect, fans, resulting in memes, particularlly image macros, referencing it. Many of these used the Advice Animal style, showing an image of Shepard’s head in the center surrounded by text with a variation of the phrase “I’m Commander Shepard, and this is my favorite store on the citadel” with “store” and “citadel” often changed.
On January 31st, 2010, Giant Bomb forum user LeBart replied to a thread discussing the funniest moments from Mass Effect 2, writing, “Going from store to store on the Citadel, and hearing this every time:” followed by an image macro with Shepard’s head saying, “I’m Commander Shepard, and this is my favorite store on the citadel” (shown below). This is the earliest known Advice Animal style “I’m Commander Shepard” meme.
The scene also resulted in a number of video edits on YouTube. On February 5th, YouTuber shadowtrooper21 posted a video of the above image macro combined with Shepard’s voice clip from the game, garnering over 200,000 views in 11 years (shown below, left).
On February 8th, YouTuber Dowza uploaded a video remixing the clip in which Shepard claims that a number of properties are his favorite, garnering over 123,000 views in 11 years (shown below, right).
Beyond Advice Animal memes, the phrase also became popular in demotivational posters and more general image macros (examples from 2011 shown below, left and right).
Source: https://knowyourmeme.com/memes/im-commander-shepard