Burping the nipples is actually pretty important.
When you replace the plugs wires and then go to put them on the distributor cap they will most always try and back out because of the air thats trapped in there.
Just take a small phillips screw driver or some such thing and push it in between the wire and the nipple,or boot if you want to call it that,and let the air escape.
If its quite in youre shop or wherever you can hear the air phsst out, plus you have the added bonus of making a good seal to keep water out of it as it will make a vacumn of sorts to keep it on tight.