Crash, pass out, conk out, whack, smack, slug, fatigue, burn out, knock out, doze off, sack out, clobber, bash, drain, wear out, and deplete.
Example Sentences of Zonk
After the marathon, he just wanted to zonk out on the couch.
He zonked so hard that he missed the alarm.
After a busy day, she zonked in her bed.
They zonked in front of the TV all weekend.
The baby zonked as soon as she was fed.
He zonked out on the sofa without changing clothes.
The dog zonked out after playing all afternoon.
I zonked quickly once I hit the pillow.