rear up
Upper Intermediate (B2)neutral
To stand up tall suddenly (like a horse standing on its back legs), or for a problem to suddenly appear.
"The stallion reared up dramatically when the starting gun fired."
Hear it in context

Who are the Monster Snakes? (Full Episode) | Monster Snakes | Nat Geo Animals
Nat Geo Animals · 8:34
to actually rear up out of the water and strike.

The Plane That's 38% Nose
Real Engineering · 3:32
This effect, called Mac tuck, tends to pull the rear up,

Hilarious Female Led Comedies You Must Watch | Big Screen Laughs
Big Screen Laughs · 30:47
I would like to rear up and jack knife my legs

Best of Judd Apatow's Movies | Knocked Up, 40 Year Old Virgin & More | Big Screen Laughs
Big Screen Laughs · 23:24
I would like to rear UP AND JACK KNIFE my legs

Epic Animal Wars | Animal Fight Night S2 & S6 MEGA Episode | Nat Geo Animals
Nat Geo Animals · 39:37
anchoring their back legs to the branch so they can rear up and spar.