This game captured a magical point in gaming where me my brother and my mother were playing on our PC, and my cousin and uncle were playing on another at the same time, keeping each other up to date on progress.
We all were blocked at the same point until my uncle found the puzzle where you have to close a door to get the keys, and as soon as he found it he phoned my mom and we all progressed.
That type of puzzle discovery hasn't happened since. Amazing game and amazing memory.
I had the same experience with a friend and Simon the Sorcerer. We would play separately and call each other to compare progress. I was happy when I beat him with about 30 minutes. I need to replay that game with my kids.
Walkthroughs in text today are OK because you can read until the first mention of something you haven't done to get unstuck, but nothing beats a real person giving you appropriate hints. Also, there's the Universal Hint System [1] that gives you more and more detailed hints when you're stuck, but I haven't used it in a real situation. I looked up a puzzle now that I was stuck on in Day of the Tentacle, but couldn't find it.
Shigero Miyamoto has talked about this about The Legend of Zelda. They purposely added secret stuff in that game with absolutely no hints, almost impossible to find for a single player, to encourage people to talk about the game in school and elsewhere. You could only find the secrets when discussing the game with others, which was what they intended. Imagine getting a hint at school and having to wait until you can run home and test it; that way you're thinking about the game all day!
Speaking of obscure, getting Washington to cut down the cherry tree by painting the fruit red got me stuck as a kid in Sweden. I hadn't heard the cherry tree myth (and now only through the game) and even if they gave hints in the dialogue, I didn't get those either. I don't even remember if I got past it or if I gave up.
I replayed the remastered game a couple of years ago on PS4 with my daughter who was seven years old, and this time the only thing I was stuck on was the cat puzzle with the squeaky mattresses. I read a blog post just now about that puzzle, and it's special because you use the Use verb on two different things outside of your inventory. You usually go inventory->world or inventory->inventory, but here it's world->world. So I had to look up that one solution in the whole game.
Playing as an adult, it's much easier to keep in mind what clues you have and what the open puzzles are. As a kid, I would just start using everything with everything else, and the hints from failed interactions wouldn't clue me in. Now I see they make a really god job at telling you why things don't work and what you should try instead.
I was pleasantly surprised that my daughter thought the game was hilarious. I expected her to get bored quickly, but we played through it all together.
The puzzle that blocked me for days was that of reading some kind of boring manual to a horse to make it sleep. I still remember myself (a kid) jumping all around the room.
We all were blocked at the same point until my uncle found the puzzle where you have to close a door to get the keys, and as soon as he found it he phoned my mom and we all progressed.
That type of puzzle discovery hasn't happened since. Amazing game and amazing memory.