A play on words with Senator John McCain's last name, replacing CAIN with SHAME. This is one of many neologisms which have been coined as of late concerning McCain's name, as well as with Obama's name -- depending on one's political preferences with either presidential candidate.
In the 110th Congress, Senator John McShame has missed 62.6% of all Senate votes -- more than any other senator!
A shart (a fart accompanied by some liquid poo) exploding from the anus following the consumption of greasy fast food such as Mcdonald's, Long John Silver's, or Kentucky Fried Chicken.
Damn that catfish platter at Long John Silver's was greezy; it done made me Mcshart on my damn self!