Kirk and I have always been lovingly honest with our children. We would look into their beloved wee faces and croon "now darlings, you know we only had you for the slave labor, right?" and they would wrinkle their adorable noses up at us and lisp back, "of courth, and may we do the vacuuming now?"
Or something like that.
In practice they have a mixed history when it comes to household chores. Child 3 is willing, sometimes, but has a peculiar blindness to anything that is in contact with another object or surface. So it will swear absolutely that its room is clean and looks on with astonishment when I point out the bread-crumb trail of lego pieces up against the walls. Child 2 read The Gammage Cup at far too early an age and was happy to discover a fictional character who believes strongly in the "organize with heaps" method of room cleaning. Child 1 will cheerfully tidy up when pressed but is blissfully unaware of messes left behind when showers are taken or clothes changed.
We did have one glorious coup when we convinced them all that dish-washing was a terribly, terribly grown-up and exciting thing to do. Child 1 had watched one of us at the sink (taking in the unbelievable possibilities of foamy white suds and a large amount of water) and had asked if it could wash dishes some time. We wrinkled our brows and looked dubious - oh, I don't know really. Maybe when you're older, if you're really good we might let you wash dishes as a very special treat. But not now sweetheart, not yet. We spun that out for several weeks and as a reward got a full six months of happy, even grateful dishwashing. Even better, Child 2 watched the whole thing, green with envy, and tacked an extra three months on the end of that. Child 3 however managed to spread the water so far and wide that it was ruled out on the basis of collateral damage.
Apparently that's the hard way to get 'em to do things though. My parents came up with a much more simple plan. For the last week all three Children have happily weeded, stacked wood, ripped up and disposed of carpeting, removed ancient and well-glued tiles (of unknown matter - probably asbestos lightly seasoned with lead), washed walls, swabbed floors, sanded, plastered, patched and painted apparently without complaint.
I could suggest it's the kindness of their hearts and their deep and abiding love for their wonderful grandparents.
But I'm pretty sure it's the cold, hard cash.