M Burgers is a fast food restaurant first seen in the Season Eighteen episode, "Cock Magic". It is a parody of the real world fast food chain McDonald's. In "Basic Cable", the drive thru employee states that the restaurant actually is McDonald's.
The restaurant was where the boys went to lunch to discuss their excitement about the previous nights Cock Magic tournament and in obtaining a rooster of their own, later named McNuggets in honor of the menu item at the restaurant.
In "The Damned", Eric Cartman and Heidi Turner go to the restaurant while bonding over not being on social media networks any longer, due to their phones and computers being destroyed. They discover they are more alike than previously known.
Heidi and Cartman are shown at the restaurant again in "Fort Collins".
The restaurant is colored red and yellow, with booths and tables. This color and name resembles the real fast food chain McDonald's but is not named that and only referred to as M.