It was a tongue-in-cheek comment to the old Avis commercial, when Hertz and Avis were 1 and 2. Perhaps I showing my age...
I know the commercial series, but it stopped being funny more than a decade ago when Enterprise passed Hertz, and then Avis passed Hertz to slot under Enterprise. Hertz just sat there looking stupid and kept relying on inertia and nostalgia. They were going down anyway - IIRC, that new German car rental firm Sixt was just about to pass them in the US too.
Junior high "humor" c. 1972
"Wanna Hertz donut?"
Yeah--THUMP
"Hurts, don't it?"