If you do a double-take when you see or hear something strange or surprising, you hesitate for a moment before reacting to it because you wonder if you really saw or heard it.
I did a double-take when I saw her dressed in biker's gear.
double take in British English
noun
(esp in comedy) a delayed reaction by a person to a remark, situation, etc
double take in American English
US
a delayed reaction to some remark, situation, etc., in which there is at first unthinking acceptance and then startled surprise or a second glance as the real meaning or actual situation suddenly becomes clear: often used as a comic device in acting
Examples of 'double take' in a sentence
double take
Not an identical one but the kind you do a double take with.
The Sun (2007)
Fellow walkers always double take when they see him trotting along with the dogs.
The Sun (2015)
Hundreds of people from around the world have added their favourite snaps and the site is well worth a quick double take.
The Sun (2008)
She glanced up, did a double take and then realised it was me.
Times, Sunday Times (2008)
He did a double take and asked me if I could sing.