2 + 2 = fish
3 + 3 = eight
7 + 7 = triangle
No other clues. It just says “only smart people understand this”. Well, I’m a pretty smart guy but this one has me stumped.
Mirror one of each pair of numbers, then stick them together with a bit of overlap. The result is an image of the thing they’re “equal” to. (The fish is actually a stylized fish symbol.)
Take the mirror image of the second number, place it to the left of the first number, and it will look like a fish, an eight, and a triangle respectively.
D’oh! Too slow
Flip a two and superimpose it over the other 2. Flip a 3 and a 7 and match them up with their respective partners.
Hmmm. I can see the 8 and the triangle but that don’t look like no fish to me. Thanks all!
Never mind. I see the fish now.
Is Inner the only guy here who knows how to type " [ spoiler ] "? 
You’re supposed to keep adding to the puzzle, e.g.
4 + 4 = Golden Gate Bridge
0 + 0 = infinity
13 + 13 = butterfly (sort of)
1 + 1 = 1
If it makes you feel better, I’ll admit in public that it took me about 45 minutes of intense thought to figure out the “Four is cosmic” campfire game.
€ + € = probably not supposed to say…
π + π = m
1+1 = M
…
e
I got all these almost immediately, which really surprised me. I usually don’t do particularly well on such spatial reasoning puzzles.
What? What’s wrong with Pisces?
The only thing I can figure is this: If you mirror the letters and put them together, the threes look like an 8, the sevens form a triangle, and I guess the two’s form a Jesus Fish?
Yes, but I wonder if the riddle has additional meaning such as the fish representing Jesus and Christianity, the 8 for resurrection or new beginnings and the triangle for the Holy Trinity.
There’s a resurrection joke in there somewhere…
8 + 8 = 4 pack
You mean other than the thread coming back from the dead? No, there’s really no additional meanings.
I will note, however, that human beings are good at seeing patterns even when there are none. So, if it makes you feel good to believe there’s a deeper hidden message, knock yourself out. But it’s a waste of both mental capacity and faith to delve deeper into what is actually a fairly simple brain teaser.
Also, I would like to point out: the Simpsons already did it (back in 1998).
5 + 5 = my coffee table
It’s a fairly simple brain teaser if you think a certain way. I imagine most people are going to think ‘numbers, it must be a math problem’. It took me a while to even consider that there might be another way to look at it.