That'd've, one of the delightful abbreviations that can occur in the English language. A contraction of "that would have". In a sentence:
"Lucky that football didn't hit you in the groin. That'd've hurt."
This kind of multiple contraction doesn't see much use in genuine, everyday conversation. It's grammatically sound, but it's such an obscure word it barely ever crops up. I use the equally contracted wouldn't've on occasion- but I usually end up getting strange looks and told I sound "English". Oh well.
Update: Pint informs me thusly:
I don't know where you're at, but contractions like this're pretty damn common on the east coast. Some of us're smart enough to write that way, too :)
I'm assuming Pint means the East Coast of America. Could this kind of contraction be an American, rather than English predilection? Personally, I live in Australia, the land that literacy forgot, so forgive my narrow worldview. All noders with any other viewpoints are more than welcome to point out any other factual discrepancies. ^_^
Another update: SharQ tells it like it is:
Pint does mean the east coast of America. And I doubt you'll find this in the UK very often.
What's the moral of this story? 1: That I am a muppet who should have considered international phrasing earlier, and 2: That that kind of abbreviation is more common in America than in England.
Yet another update: Many people's contributions:
After a lot of very helpful and literate people messaging me, I feel it worthy to point out a few things:
1- That I am still a muppet.
2- This kind of contraction sees a lot of use in American English, apparently most concentrated in the east coast, although not uncommon in other regions.
3- It is used in England, but less commonly so.
Thank you one and all for helping this node to grow and become more factual.