Yeah,
The funny thing is if you know you are on a LAN...

and let's say they've given you an IP of

192.168.0.178

Just use another number

192.168.0.144
192.168.0.13

Or something like that. I change my number everytime i come into work. They don't have a clue what is going on

Sometimes you'll find that someone else is using that number when you try to input it, just select another number.
Simple as that.

It masks your real number. But make sure your computer name is not identifiable.. because they can track that too when you connect over the LAN.