I don't really get it.
An SD card has basically nothing in common with a floppy disk, while USB sticks are basically the same thing as a SD card, it just uses a different interface.
Is it talking about the color or the shape or something?
At first I thought this was going to be a joke about the FAT file system and then I realized it's a joke about shapes that doesn't really make any sense.
Firstly, it's a newer format, better, gooder - one could even say sleeker?
Two, it allows (by way of support) larger capacity on the same media, which would be an equivalent to lower volume and higher strength, akin to the body of a weightlifter.