OK, I'll do my best.
So: You and I are each on 5 channels.
I am on these channels: #woot, #house, #tv, #door and #chair
You are on these: #door, #chair, #tv, #alpha, and #beta
I do a whois on you:
/whois -> Kurdish_Assass1n
And in the whois there should be a line, saying this:
Common channels with Kurdish_Assass1n: #door #chair #tv
So, it checks on which channels we both are on.
Is this a better explanation?
