assume the position

Short definition from Wiktionary

Verb

1. 1
   Often used other than figuratively or idiomatically: to assume a given position.
2. 2
   To turn away, with one's hands in a visible and unmovable position, so that one can be searched.
3. 3
   Often used as an order to bend over, for example, to receive the traditional corporal punishment in a case of misbehaviour.