could (do something) standing on (your) head

informal

if you could do something standing on your head, you can do it very easily, usually because you have done it many times before.

I've done this job for so long I could do it standing on my head.

• have all the aces
• have all the answers
• have all the cards
• have all the makings of
• have all the makings of something
• have all your marbles
• have a lot going for
• have a lot going for you
• have a lot irons in the fire
• have [a lot of/a few/several etc.] strings to bow
• have [a lot of/a few/several etc.] strings to your bow
• have a lot of strings to bow
• have a lot of strings to your bow
• have a lot of time for
• have a lot of time for someone
• have a lot of time for something
• have a lot on plate
• have a lot on your plate
• have a lot to answer for
• have a memory like an elephant
• have a memory like a sieve
• have a mind like a sieve
• have a mind like a steel trap
• have a mind of its own
• have a minute to call own