in climbing terms
a jug is a big
probably named after the container.
A jug can be grabbed with the entire hand
rather than just the fingertip
It is also known as a bucket
The importance of the jug on the route
is that due to it's large size many diferent
forearm, arm and shoulder muscle groups can be used to
hold on to it with. Usually only a few of these
muscles are being used to exhaustion on a climb.
When you reach a jug you can transfer you weight around
and in so doing can rest the muscle groups which are near to failure. This is called shaking out the pump.
Often a climber will be
heard to mutter
"where's the jug, where's the jug
where's the fucking jug" just before
they fall off the route.