Heard of this grease fitting?

[Tinhack]

Those were the original "quick connect" fittings. The lube kit I got for my electric grease gun has a lock-on attachment similar to that but for standard grease fittings. It slides on and locks onto the fitting from the side. Its handy for hard-to-reach fittings or fittings where you can't get a "Lock-N-Lube" on.