Seized handbrake lever on rear caliper...

[Frederick Smith]

A Zerk fitting is a common grease fitting that enables you to attach
a grease gun coupling for the purpose of....greasing. Kind if a nipple
with a spring mounted ball in the tip that prevents the grease from 
escaping after the coupling is removed. Zerk was probably the name
of the original inventor/manufacturer that then became the name that 
became the "common" name for that type of device. Kind of like "Bondo"
becoming the word used to describe plastic body fillers by any 
manufacturer. 

Smitty