Caterpie, Cyndaquil and the male Charizard are from Nintendo's Pokemon, the female Flamedramon's from Toei's Digimon and this screenshot's taken from Valve's Garry's Mod. It is supposed to be a post-inflation and "popping" themed image.

Looks like Charizard and Flamedramon were at the dragon belly inflating competition again and, this time, their fiery powers went overloaded, causing them to explode like a bomb, returning their sizes back to normal as well as instantly knocking them out and see stars around their heads and cause their respective and gigantic Fire Blast and Fire Rocket to send flying into the sky. Meanwhile, Caterpie and the brave little Cyndaquil were watching and are very surprised to see this crazy situation just happened.