On which tool is mushrooming most likely to occur when working as a plumber?

Define"Mushrooming".

Love to know what test you are taking?

Hi all:

Just for fun I thought I would pop in and try an answer to the question... ;)

The tool most often "mushroomed" in plumbing will probably be a cold chisel or a caulking iron... see image below.

If you install and remove a lot of boilers you may also have a wedge where the head gets mushroomed over fom hitting it so hard with a sledgehammer.

Let us know more...

Mark