WordNet
high sign
n. a silent signal of warning or recognition; "she started to speak but he gave her the high sign"
Usage examples of "high sign".
Give me the high sign if he tells her to take the dogs with her,”.
She squinted at the two-story-high sign and nodded automatically, even though there was no way for the person on the other end of that phone call to see her doing so.
A two-story-high sign out front proclaimed it to be the Serene Temple of Unfailing Lifescores.
Sperin gave him the high sign to give her a drink as arranged, and to tell her it was from him.
If that guy puts in an appearance again and you sense him before I see him, give me the high sign.