double take. do a double take. His parents did a double take when he came home with a tattoo.

 

double take

noun

dou·​ble take ˈdə-bəl-ˌtāk 

: a delayed reaction to a surprising or significant situation after an initial failure to notice anything unusual 

—usually used in the phrase do a double take

His parents did a double take when he came home with a tattoo.