At 6-foot-5, and hovering around 350 pounds, Wesley Willis is an imposing sight. The spectacle is only enhanced by a ragged afro and the fact that he enjoys greeting people with a head butt. His massive size belies a gentle demeanor, for Willis only wants to “rock,” and for you to enjoy it. Witness the extravaganza Tuesday night at the Orpheum.

Found on the streets of Chicago — literally — Willis has been termed an “idiot savant” and a “genius” for what are seemingly profane nursery rhymes. While homeless in the windy city, Willis would sell heavily detailed pen-and-ink drawings of the surrounding urban scenery; some of them serve as his album covers.

In 1989, Willis was diagnosed with chronic schizophrenia and says his music held quiet the voices in his head. Then, in 1992, guitarist Dale Meiners befriended Willis and the two formed The Wesley Willis Fiasco. Willis later signed with American Recordings. He’s recorded more than 20 albums featuring more than 400 songs.

Most of his albums were recorded in less than five hours, and at times he has had up to four new albums in circulation. On 1993’s Rush Hour, Willis exclaims, “I am a rock. I am a roll.” And he has no qualms about selling his CDs; he will walk right up to you and ask if you’ve bought his album yet. Willis will also ask you to say “rock,” and will smile approvingly when you do.

He has recorded tracks as a member of The Wesley Willis Fiasco, a hardcore metal/funk band, and also as a solo artist. While fronting The Fiasco, Willis stands on stage with a lyric sheet and just yells the words over the instrumentation. The Fiasco has even opened for Pearl Jam in Chicago-area concerts.

Most of Willis’ songs follow the same blueprint. Willis uses a Technics KN-2000 keyboard straight out of 1989, and programs slight deviations in tempo and melody. He also has the same preset rhythm (country rock 8) for every song.

He barks out a four-line verse, in which none of the lines rhyme. If some lines do rhyme, it’s purely coincidental. This is followed by the chorus: Willis repeatedly yelling the title of the song as loudly as possible. Then there is another verse, another chorus, and then a near comical keyboard breakdown. After one more set of verse-and-chorus, he finishes the song with a tag-line from an advertisement, such as, “I love what you do for me — Toyota!”

His song titles span the spectrum from hilarity to hypochondria. “Cut that Mullet” and “Rock ‘N’ Roll McDonald’s” are pure kitsch, while more disturbing tracks include “I’m Sorry I got Fat” and “They Threw Me out of Church.” And then there’s “I Whupped Batman’s Ass,” and its sequel, “I Whupped Superman’s Ass,” which really need no explanations. Willis also likes to make references to bizarre animals, such as bactarian camels and snow leopards, and how these animals “rock.” Most songs have lyrics that are entirely unprintable, but inlcuded here are the lyrics to “The Chicken Cow,” so you could get a sense of his unique talent.

Tuesday’s show at the Orpheum starts at 9 p.m. and tickets cost $8-9. Be sure to get there early, because Willis’ shows routinely sell out.

Contact Andrew Pinaat oracletunes@yahoo.com