I'm a SAHD and have been on - and off for 6 years.
It's harder than any job I have done and I'm used to being asked this type of question by male mates etc. but non of them are prepared to swap for a week. :-)
But twice in the last 2 weeks I've been asked this question by recently returned to work ex SAHMs. I was gobsmacked and more pissed of with them as they should know what I do, and no they weren't joking.