My attempts at fooling the kids:
ME: When we get home we need to clean the toilets and mop the floors.
TABBY: Oooh! Can I help mom the floors?!
(April Fools fail #1)
ME: When we get home we're getting on pjs and going straight to bed! I'm tired!
ZEAL: (sounding a little bummed, but not too much) Oh. Okay.
(April Fools fail #2)
ME: You guys are growing too much. I'm not going to feed you any more!
TABBY: No! That's not nice.
ME: Yups. Only going to give you water.
TABBY: Oh, well if we get water...
(April Fools fail #3)
ME: We get cupcakes for dinner.
(bring them out and serve them...kids eyes light up)
ZEAL: (tasting 'cupcake') Mom, are you April Foolsn me?!
(April Fools success!)