Because they can never be a part of the solution.
Ask him/her to pronounce unionized
Because the reaction could be explosive.
Wife: He makes friends with the strangest things Me petting a bee: You're not strange are you Alan
It taint yours and it taint mine :D (Puns for the win :D)
A problem. What do you call when 3 terrorists are on the moon? A problem. What do you call when all the terrorists are on the moon? A solution.