BJ Penn and Rory MacDonald are scheduled in the main event of UFC on FOX 5 on Dec. 8. The two are sparring on Twitter, initiated when MacDonald announced he was 200 pounds and trim ahead of their welterweight contest.

Rory MacDonald ‏@rory_macdonald

200lbs and @bjpenndotcom thinks i care if hes in shape for the fight or not #newgenerationmindset

BJ PENN ‏@bjpenndotcom

Great!!! I frekin love knocking out 200 pounders

Rory MacDonald ‏@rory_macdonald

Do u meen knockin back quarter pounders? Who r u kidding, certainly not yourself ?

BJ PENN ‏@bjpenndotcom

Quarter pounders?? Really pimple boy? I won’t even RNC you… afraid of all the pimples on your back. #GROSS

Rory MacDonald ‏@rory_macdonald

I didnt think it was possible but somehow u made yourself even less of a threat.