It’s a shitposting meme. The poster has this pinned on their twitter:
That said… I have heard horror stories about poor theater staff finding cucumbers after the 50 shades premiere. Some of it was just people memeing and trying to prank but I’m not entirely sure about all of it.
I can’t see the kid’s face clearly enough to tell if they’re having the time of their lives or if they’re absolutely terrified.