GRIM REAPER WORDS
GRIM REAPER is a euphemism for DEATH. Euphemisms are words that are used when we don’t want to name a phenomenon directly because of some ethic considerations. Here are some more slang euphemisms to use when we talk about subjects that are awkward or embarrassing. Use them and make your teachers happy. Or not.
Here is a dialogue as an example:

— Jerry? Your dog is puking on your new carpet.
— Is she? I’ll be right there.
— Hey Jerry. The dog is really sick. Now she’s got the runs.
— I’m coming.
— Jerry. Get in here. He’s gone belly-up now. I think he’s passed out.
— Oh, look. I think he popped his clogs.
— Bummer. He totally bought the farm.

There are different various slang impressions for illnesses and death:
The runs (noun) diarrhea; liquid poop
Pass out phrasal verb to faint
Puke verb vomit. Other expressions for this are barf, hurl, and toss your cookies. Puke and Barf are also nouns.

Pass out phrasal verb faint, lose consciousness (sometimes as a result of drugs or alcohol)
Buy the farm die

Go belly up
Although this idiom sometimes means “die”, it more often means “fail” (for a business) or “stop working” (for a machine): “You gave me a link to a web-site and it has gone belly-up.”

Other slang terms described things that have failed or stopped working:

I have a bad feeling that my computer is about to crap out on me. — I am afraid the computer is about to stop working.
My sleep schedule is completely out of whack. — My sleep schedule is out of order.
Look, my fridge is kaput! — my fridge has broken.

The word FUCK that you should never pronounce, being a decent person, nevertheless must be understood in some contexts:
If you want to say that someone used that word you may say that he used an “f-word”, or threw an “f-bomb.”