Tic
A tic is a sudden, repetitive, nonrhythmic motor movement or vocalization involving discrete muscle groups. Tics can be invisible to the observer, such as abdominal tensing or toe crunching. Common motor and phonic tics are, respectively, eye blinking and throat clearing.
Tailwhip
The tailwhip is a bike trick typically performed on a BMX, in which the frame of the bike performs a complete rotation around the front end (bars and forks), which remains stationary throughout the move. The same trick may also be performed on a kick scooter.