Does anyone know about avaya check scams?

I found some people from the UK that are saying they will pay me %10 of whatever a client owes them in order for them to avoid a %25 tax from their government. All I have to do is cash the check(in my case two checks, each $1,999.99) and send them the money via money gram or western union. Well I was about to do it and my dad wouldn't let me telling me its a scam. He called one of his friends and his friend told him that the same thing happened to his son, I guess what happens is that there are off shore accounts with funds that disappear after about 24 hours, leaving me with the $4,000 debt. I know I really summed this up and it might not make sense but I need to know if there is anyone who has heard of this or gone through with this that might be able to help me.