'to bill' means to smoke, more specifically weed. Not really a common word but used in quite a lot of songs

Large, beautiful breasts that are keep well consealed and initially appear to be much smaller and less impressive than they actually are until unleashed.

'to bill' means to catch a fish, take off your boot, then proceed to take your boot and put the fish inside. After the fish is in your boot you pull down your pants and fuck the live fish until your penis ends up killing the fish from suffocation, internal bleeding, and heart failure. Not really a common word but used when fishing by yourself and sexually frustrated.