[BroJoeK]

It appears that the shorter vulgar term is actually older, originating with Norse berserkers, when they weren't fighting.
So the longer form came later, perhaps in an effort to gussy up the old girl with a more respectable prefix, and a somewhat different meaning, now surprised, distressed or confused as in romance.

Turns out, the word is not always vulgar.
A village in the Shetland Islands;-)

[Tax-chick]

Very interesting, thank you!