Marvin’s birthday cake:

based on Marvin’s book:

and created by these folks.

I think they did an amazing job.

I suggested the “zero to infinity” since it’s what you get if you turn “80” sideways. I had in mind a “zero” over the “lazy” eight, $$0 \atop \infty$$, but I think it’s more readable as it was translated through two phone calls into the image above.