In the last three years, I have caught 4 20"+ bass:
1) Was fishing from the bank at the pond at my housing development (you are not supposed to fish there unless your property is on the lake, but since it was not completely built up, I used to sneak down there and catch a few). Had been hitting some 10" to 14" bass on a regular basis and had caught a few nice blue gill when I felt a thump and new it was a good'en. Tried to reel him in and he kept taking drag (though my reel was broken ). When he jumped I almost had a heart attack. Managed to get him landed and had to estimate the length/girth: approximately 21.5"/16" -- 6.15# by the fish weight calculator on this website.
2) Fishing a tournament at a local lake. Had been having some luck from shore on a particular bank but one of our guys had camped out on this spot and stayed there for a couple of hours. Wasn't doing much good elsewhere and so decided to move in after he left. On the first cast, caugt a 20.5" . Didn't get the girth measurement, but he was a realy hog.
3) Earlier this year I was fishing at my test pond. Lots of people fishing there in the Spring with worms and buzz baits. The weeds were starting to get thick and decided maybe I could get some bites by crashing a crank bait into the weeds. First cast, felt the fish bite, but he didn't hook up. Threw down my crankbait rod and followed with a 6" Vibra Tail worm and he took it (no more than 10' of line out) and he nearly ripped my arm off. Measured him at 20.5" with a 16" girth (just under 6#)
4) About a week ago, I was fishing over my lunch hour at a lake near my work. I had been fishing the weeds, but the blue gill were pestering me so bad, I decided to just have a little fun and tied on a 4" GULP Nightcrawler and let the blue gill drag it around. On my second pitch, I felt a pretty good tug and thought it must be big BG. Pitched again and felt the hookup, reeled him in and was shocked to see a giant mouth. I had to estimate his length at somewhere between 20" and 21", an easy 5#er.