Brown 1/2 lb of bacon, drain, cool and break up into pieces. If you don't want to use real bacon buy a 1 pkg of bacon bits and they work just good. Brown 1 lb of hamburger and 1 cup of chopped onion. Put those three ingredients into a slow cooker.
Add the kidney beans, northern beans, pork & beans, ketchup, brown sugar, vinegar, and salt & pepper to slow cooker. Salt and pepper is for taste so add more or less as needed for flavor.
Cook in slow cooker for 2-2 1/2 hours making sure juices are not too soupy.