Muhammad Ali, (born Cassius Marcellus Clay, Jr.; January 17, 1942 – June 3, 2016) was an American former professional boxer. Ali was diagnosed with Parkinson's syndrome in 1984, a disease that is common to head trauma from activities such as boxing.
Peter says Lois “floats like a butterfly and stings like when I pee” in "Lethal Weapons", a reference to Muhammad Ali’s quote “Floats like a butterfly, stings like a bee.”
The picture in the newspaper of Lois standing over her fallen opponent in "Baby, You Knock Me Out" is a reference to a photograph of Muhammad Ali standing over Sonny Liston after their second fight.
in "Baking Bad", Peter and Lois mention George Foreman's boxing career and his grill, as well as expressing surprise that he is doing better than Muhammad Ali, who beat him in 1974 to take back the heavyweight boxing title.
In "Peter's Sister", when Peter is afraid to face his sister Karen Griffin over her bullying, Meg questions what would have happened if Muhammad Ali had quit boxing. A cutaway shows Ali in good health, greeting his grandchildren and able to enjoy soup without the shaking that accompanies Parkinson's.