The uppercase R is the most obvious one to me, which interestingly is the only one I prefer Arial over Helvetica. I sometimes like to screw with font nerds I kn

The uppercase R is the most obvious one to me, which interestingly is the only one I prefer Arial over Helvetica. I sometimes like to screw with font nerds I know and make the R be Arial and the others Helvetica and see if they notice (they of course notice the R, but don’t always immediately realize the joke).