question about pumps, pattos and such things..

There is a fair bit of noise about Pattos turning on pumps, both here on ANP and other stocks too recently...

Also now talk of Melbourne Pump crews...

Thought I'd check with my broker on how heavy Patterson Securities were in the market on the big breakout day on the 23rd...

Turns out they were hardly in the market at all!!

So what is the deal they 'pump' the stock through other brokers? Then sell through other brokers again?

...and what is with this mysterious 'pump' crew from Melbourne. How do you know they exist?

Is this legal?

Many thanks in advance. Been reading lots about pumps and such things on so many threads last few months got a little curious...