This commercial happened:
This poor man's Denis Leary pissed off viewers, as it seemed he was threatening to have his cougar kill anyone who tried to serve him another beer.
I found the commercial to be stupid, but honestly it wouldn't have been memorable to me, had I been an adult in the '70s.
Regardless, this went over so badly (as did a similar commercial involving a boxer) that people started abandoning the Schlitz brand in droves, and eventually they sold the entire company to Stroh Brewing Company.
I remembered seeing Schlitz everywhere as a kid, and I heard a reference to it on "F is for Family" (set in 1974), so I decided to look up what happened to it.