"Mega Man" (or "Megaman") is a song written by Pat Wilson. Initially conceived as an instrumental, the song received lyrics later when recorded as a song for 60 Wrong Sausages. It appeared on the band's demo Cholesterol EP. Karl Koch briefly described the song in a 2008 interview:
[...]Pat's song "Megaman", I've always loved. He originally did an instrumental of it at our apartment on Stoner; he did it on a 4-track, and I remember him emerging from a bedroom, one of our two bedrooms, with this big smile on his face and he was like "You gotta check this out." It was just this distorted drumbeat from an HR16 drum machine, and a little, quick bass line and these two guitar parts that had these crazy, like, rotary flange effects on them, and it was the coolest song ever. We were all like "Yeah! What's it called?" and he was like "Megaman!" But there was no lyrics at that time. Later, 60 Wrong Sausages did a demo with lyrics, which was also good, but I remember being super stoked on that.
According to the Recording History, the song was demoed during Weezer's initial rehearsal, with Pat on vocals. The song may have been performed live (also with Pat on lead vocals) at Weezer's first show at the Hollywood club Raji's on March 19, 1992, but this cannot be confirmed as no recording exists.