There was no reaction
They get a fangover.
It cracked.
They're the one with the dirtiest knees
Damn! (This is my go-to joke that someone told me in highschool like 7 years ago. Felt like sharing it.)
Clickbait. Edit: Added a space which triggered someone.
You can mash potatoes, but you can't pee soup. (sorry sorry. Really. I've loved this joke since I was... oh.. six...)
Because the reaction could be explosive.
Their jobs get a lot easier when there are no reactions
A: Because if you can't Curium or Helium them, you Barium!
Well, if you can't helium and you can't curium, all you can do is barium!