do something standing on one’s head—(coll.) do smth. very easily or without effort (also: do something on one’s head):
- The climb he wanted me to attempt was a simple one. At Cambridge I could have done it standing on my head.
stand on one’s head doing something—(coll.) do everything possible; do all in one’s power:
- He stood on his head trying to explain to her why he was so late, but she still didn’t believe him.