Though frowned upon in formal writing, contractions can be very useful in speech, words such as...

aren't (are not), don't (do not), isn't (is not), wasn't (was not), can't (cannot), weren't (were not), wouldn't (would not), doesn't (does not), hasn't (has not), haven't (have not), couldn't (could not), shan't (shall not), I'll (I will/I shall), you'll (you will/you shall), he'll (he will/he shall), she'll (she will/she shall), they'll (they will/they shall), Bob'll (Bob will/Bob shall), The horse'll (The horse will/the horse shall), I'm (I am), you're (you are), who's (who is/who has), he's (he is), she's (she is), it's (it is/it has), we're (we are), they're (they are), I've (I have), he's (he is/he has), you've (you have), we've (we have), they've (they have), I'd (I would/I had), he'd (he would/he had), she'd (she would/she had), you'd (you would/you had), we'd (we would/we had), they'd (they would/they had).

In speech you will often alos hear double contractions such as they'll've (They will have). So, I'd like to propose the following quadruple contraction for everyday usage:

they'lln't've'd (they will not have had) pronunciation: thay-uhl-uhnt-uhv-uhd

It can be used in everyday speech like so:

they'lln't've'd time to eat before they get here so we should prepare something.

So why not use it today, about 43 times.