LOL! It's funny because the guy in the hat is Alex Hirsh and he created Gravity Falls and he's dressed like Grunkle Stan because he voices him and also Bill Cipher is best character ever u noobs ROFL! #BringBackTheFalls
This is what happens when you let Mabel watch Up! and give her access to the party balloons and helium.
Anyone who still has a Gravity Falls-shaped hole in their hearts should try plugging it up with Stranger Things on Netflix. It's by no means better than Gravity Falls, but it'll sate your fix for little kids solving a series-long mystery in a small backwoods town where strange things happen. (And it's a creation by Steven Spielberg dripping with 1980s nostalgia!)
I can totes see these two cosplaying as Over the Garden Wall for Halloween.
If Bill Cipher managed to master multi-dimensional travel and team up with his alternate dimension selves, reality would be doomed!