People aren’t exactly jumping all over this thread with jokes, are they?
A) Even when I see the opportunity, I no longer feel the need to whip out the joke all the time.
B) When I do that, it usually makes people groan.
C) Every list needs at least three members.
D) I always try to include at least four: help me everyone, try to think of a D.
That’s what she said.
It’s one of those things that can be funny, even extremely so, but only in the right context. And the right context can’t really be conveyed to a bunch of strangers after the fact. In order for it to be funny, you have to know the personalities of all those who were present, and the relationships between them, and see their reactions, and so on.
I liked that the guy used the term “Wellerism” in his accompanying Youtube video.
Once again you don’t seem to be understanding what I wrote. I didn’t call you an idiot. I said that if you use it the way you said you were going to in the OP you would look like an idiot. And you asked for people’s opinions here. Now you don’t like ones that differ from yours.
You didn’t say that if it’s done right, it’s funny. What you said was:
This is the problem. I’ve used the joke myself on occasion. To be funny, it has to be in exactly the right context, as people have tried to explain to you. But personally, I use it mainly ironically, as a groaner, like a dad joke or an extremely bad pun.
Obviously your mileage varies greatly from mine. I don’t find this at all funny. It’s not even a real example of the joke. Basically, for the classic joke, you start off with a statement that doesn’t sound risque. By adding “That’s what he/she said,” you are pointing out that the statement can be taken another way, and making a double entendre. Your joke is a single entendre. Your friend reacts with horror, and then your hypothetical “he” reacts in exactly the same way.
That’s what OpalCat said!
You are right Colibri and I am sorry I misread your meaning. It doesn’t seem funny at all now. It was late and I had not gotten much sleep over the weekned. I became Michael Scott!
See. That’s exactly my point. Michael Scott is funny because he doesn’t really know how to be funny. He’s socially oblivious. You don’t want to copy Michael Scott if you want to be actually funny. 
I think the joke can be funny in two instances. First, you find a new and unexpected double entendre to make. Something outlandish that has never been the subject of the joke before. These opportunities are rare. But it’s not funny if you just reflexively repeat it every time someone says “I found it hard” or “Gosh I’m hot.”
Second, you can use it ironically, in an effort to be goofy. But it’s easy to overuse this. In any case you shouldn’t use it “on every possible occasion.” In that case you’ll end up like Michael Scott, and the only one who will laugh is Dwight.
to continue beating this dead joke to death, when I wrote the OP I didn’t think about it much, I just threw it out there. I said “That’s what he said” in response to my friend saying “Yikes.” But that is exactly what he said, my “joke” was the opposite of a joke. Wish I could say I meant it ironically at the time.
Using the joke ironically as Michael Scott could work, except most people would not know you are being ironic. I’m going to treat this joke the way a lot of people treat the pronunciation of “banal.” They use another word so as to avoid a discussion of the proper pronunciation.
A perfect example just came up in a work email. Client says “I will be make sure to poke a bit to get an answer as soon as possible.”
Now of course I would never make that obvious joke to a client, or anyone for that matter. It is too obvious. But let’s just assume I lived in a world where it woul be OK to make that joke to a client. I would do it ironically, because Michael Scott would have made the joke. But she probabaly would not have taken it that way, I would have to say, "As Michael Scott would say, “That’s what he said.” But if you explain a joke, it’s not funny.
I remember Alan Swan in “My Favorite Year”, quoting an English actor - "Dying is easy, comedy is hard. "
Irony is even harder.
No joke.
A perfect example just came up in a work email. Client says “I will be make sure to poke a bit to get an answer as soon as possible.”
Now of course I would never make that obvious joke to a client, or anyone for that matter. It is too obvious. But let’s just assume I lived in a world where it woul be OK to make that joke to a client. I would do it ironically, because Michael Scott would have made the joke. But she probabaly would not have taken it that way, I would have to say, "As Michael Scott would say, thinking he is being funny, “That’s what he said.” But if you explain a joke, it’s not funny.
I remember Alan Swan in “My Favorite Year”, quoting an English actor - "Dying is easy, comedy is hard. "
Irony is even harder.
No joke.
At work I use it for every response, just in case.
“Oh damn, the photocopier is buggered up again”
“That’s what she said!”
I’ve used it a jillion times not so much because it happens every day, but because I’m old.
My last one came a few months ago when I passed an ad for a stump-removal service, and above the phone number was the text: “Need a grinder?” A rare “that’s what HE said!” opportunity.
I had someone use that line on me: “Don’t you like any new bands?” My reply: “Well, those Traveling Willburys are kind of good.”
Trump: We should just shoot all the protesters!
Me: That’s what Xi said.
It works well for huge assholes.