Matthew Kowalewski, better known as Matt McMuscles, is a YouTube gamer and game commentator, better known as one of the co-founders of the YouTube channel Super Best Friends Play. He appeared as a guest on Grumpcade in the episode "Spider-Man 3 The Game".
- He narrated the video about Final Fight for Did You Know Gaming? which was written by lovelie Vitas Varnas.
- He appears as a portrait in the Hall of Champions level in Shovel Knight.
- Matt appears In SkullGirls in the form of a background character that randomly shows up in the River King Casino level. He can be seen alongside Woolie as the two appear to have a lot of money in their hands.
- This was likely because Matt and Woolie donated $2,500 to help fund SkullGirls.
- When recording with the Grumps Matt was profoundly upset Arin managed to finish the quick time event in Spider-Man 3. Apparently the death animation that involves a woman dying and Spider-Man face-planting is hilarious.
- Matt is a talented artist who was an active member of Deviant Art prior to his career in video game QA.
- He once brought a copy of Street Fighter that had stolen cover art he drew. He later found out the person that was selling these games did put a link to his DA account on the artwork.