I would add to the rules of swear word combos, there should be alliteration, to give the combo rhythm, and lend a beat poet kind of feel to it. The combo should trip lightly of the tongue, syllables rippling through the air, without hesitation, repitition or deviation, using all the sweets from your box of loquacious allsorts...

For instance, one I use daily, and first thought of when I knocked over a piece of equipment worth 10,000 quid :-

Blue blistering, shag arsed FUCK!
And another :-

Monkey futtering SHAG STICKS!