Two friends join the SAS.

Two friends, Pat and Mick, are trying to join the SAS. After doing all the training their commanding officer in charge tells them, "Now you two must realise that you have to do anything your commanding officer says no question asked, so Mick go into that room there", so Mick walks in. The officer then says to Pat, "Do you think you could kill a friend Pat?", to which Pat replies, "oh no I love all my friends"
"WHAT DID I JUST SAY PAT!"
"Yes sir!" Pat exclaims.
The officer then says, "Do you think you could kill Mick, Pat?"
"Oh never sir Mick is like a brother to me I have kno..."
"WHAT DID I JUST SAY!!"
"Oh right, yes sir"
"Well then take this gun, and walk into that room, where you shall kill Mick", so Pat goes in and 5 minutes later he goes back to his commanding officer and he says, "I've done it sir"
"Well you'll be glad to know that gun was fake Pat and just call Mick back in"
Pat then replies, "I can't sir"
"Why?"
"I strangled him"