Baby Gramps is a complete enigma. Who is this man behind a wide brimmed hat and long gray beard? He looks just as comfortable busking on the street corner at Pike Place Market as he did performing on David Letterman’s stage. He could be a homeless beggar or a renowned folk singer. He’s definitely unlike any other performer you are likely to see. He makes sounds never before heard coming from an American folk singer. In between lyrics he uses his voice as a third instrument — perhaps a tuba. He is one part Tuvan throat-singer, one part guitar genius, one part rodeo clown and three parts unfiltered energy. He performs a distinctive bobble-headed dance; he stomps his foot and swings his arm around between guitar strokes while remaining seated in his chair. He revs up his audience and draws them into sing-alongs. He makes silly jokes such as, “I haven’t had this much fun since I fell off my dinosaur.”

What is still a mystery is, when he was younger, did people find it strange calling him Gramps? Or is a prematurely graying young man hiding behind the dark glasses and wide brimmed hat? Because if he shaved his beard and bared his head, only his mother and Santa Claus would recognize him.

[Bob’s Java Jive, Saturday, April 28, 9 p.m., $5, 2102 South Tacoma Way, Tacoma, 253.475.9843]