cello-ing 

(verb) The act of playing the cello, a musical instrument with 4 strings.

Why did you call me when I was cello-ing?

cello-ing by asdfkjh June 19, 2010

celloing 

becoming a zombie and taking over the world through a two step plan

Sorry man, I can’t hang out today. Too busy celloing.

celloing by twostepplan May 22, 2018