twid·dle 
/ˈtwɪdl̟/ verb
twid·dles; twid·dled; twid·dling /ˈtwɪdl̟/ verb : to turn (something) back and forth slightly [+ obj] ▪ Just twiddle the dial on the radio a bit for better reception. ▪ Twiddle the knob on the telescope until things are in focus. ▪ She twiddled her pen while she talked on the phone. [no obj] ▪ She twiddled with her pen while she talked on the phone.
twiddle your thumbs
informal : to do nothing : to waste time while you wait for something to happen
▪ I was just twiddling my thumbs until the phone rang.
▪ I was just twiddling my thumbs until the phone rang.
— twiddle noun, plural twiddles [count] Brit
▪ Give the knob a twiddle.
▪ Give the knob a twiddle.
