“Shoutouts to SimpleFlips” is a phrase used when one shouts out the twitch live-streamer “SimpleFlips”. This phrase is most used on SM64 speedruns and romhacks.
"Shoutout to SimpleFlips" was created when SimpleFlips could not attend a speedrunning event in which he told his friends to 'shout him out' due to him not making it.
On April 1st, 2016, a ROM hack of Super Mario 64 called “Super Ultra Kaizo Memeio Road 128 Stars Extreme Edition Revenge Deluxe” was uploaded to google drive by the user Kaze Emanuar.
Within this hack, Mario is stuck in a wheelchair and many memes are scattered throughout the game. (i.e. “my b”, John Cena’s theme, and of course, “Shoutouts to SimpleFlips” which replaces nearly every text box in the game.)
On May 9th, 2016, Twitch user Vargskelethor (a.k.a. Vinesause Joel) streamed the hack and later uploaded a Highlight video to Youtube. This video got quite a lot of views and thus "Shoutouts to SimpleFlips" was popularised.
Since then, many ROM hacks have been created featuring the phrase