Who would pay the IRS with Money Gram? Idiots! Call these guys back and play along, it's rather entertaining. If you record it put it on Youtube, makes for some great evening entertainment.
Several calls in the last two days. IRS has filed a lawsuit against you. This happen last year around the same time. Please don't call these people back. Scam and some poor unsuspecting victim will fall prey. Shame on these thieves!