Parent: It's time to brush teeth!

Toddler: I no want brush teef!

vs:

Parent: It's time to brush...

Toddler: Teef!

Similarly, "the dirty tissue goes in the...", "when we get home it will be time to put pee in the...", "it's time to eat...", etc. My experience is that, at the right age, kids just really love getting to complete things, and this somehow spills over into their attitude towards the thing they're completing. Or having it come from their mouth somehow manufactures buy-in, or skips the normal opportunity for them to (as is also common at this age) say no?

One nice safeguard this has is that while it's mildly manipulative, once they lose their joy at completing things it stops working. So it doesn't have the risk that you'll keep using it at an age where (in my opinion) manipulating kids starts to be a problem.