Aaron R. Reynolds apparently had the obsession with hiding a signature in his code (like the AARD one being referred to here).

Other places where you stumble across the name include e.g. FAT32 which has a filesystem information sector[1] in the hidden region after the boot sector which includes similar signatures (AaRR and aArr, byte swapped to little endian of course).

[1] https://wiki.osdev.org/FAT32#FSInfo_Structure_.28FAT32_only....