straighten up
phrasal verb
straightened up;
straightening up;
straightens up
Definition of straighten up
1
: to make (something) organized or tidy : to put (something) in order
They straightened up the house after the party.
2
: to move the body to an upright position
Straighten up. There's no excuse for slouching.
3
US
: to improve in behavior
You need to straighten up, young man.