"Unexplainable" joke

A farmer is sitting in the local pub inebriated. A man comes in and asks the farmer, “Hey, why are you sitting here on this beautiful day getting drunk? ”
Farmer: Some things you just can’t explain.
Man: So what happened that is so horrible?
Farmer: Well if you must know, today I was sitting by my cow milking her. Just as I go the bucket about full, she took her left leg and kicked it over.
Man: That’s not so bad, what’s the big deal?
Farmer: Some things you just can’t explain.
Man: So then what happened.
Farmer: I took her left leg and tied it to the post on the left with some rope. Then I sat down and continued to milk her. Just as I got the bucket about full she took her right leg and kicked it over.
Man: Again?
Farmer: Something’s ya just can’t explain.
Man: So, what did you do then?
Farmer: I took her right leg and tied it to the post on the right.
Man: So then what did you do?
Farmer: I sat back down and continued to milk her, and just as I got the bucket just about full, the stupid cow knocks over the bucket with her tail.
Man: Wow you must have been pretty upset!
Farmer: Some things you just can’t explain.
Man: So then what did you do.
Farmer: Well I didn’t have any more rope, so I took off my belt and tied her tail to the rafter. In that moment, my pants fell down and my wife walked in.