Sleep's really my choice, but I had to vote for knuffelen(1) since aside from lekker(2) with accompanying hand motion(3) it's the best Dutch word for non-Dutch people.

(1) snuggling.
(2) delicious/succulent/enjoyable/good
(3) There's a hand motion that goes along with lekker when you're talking about food. Some people have a hard time noticing that the rest of the world has no idea what's going on when they wave their hand frantically over their ear while stuffing their mouthes.