I had the same question. It's my biggest pet peeve when articles go on with cryptic acronyms (or, in this case, initialisms) and don't explain them.

The Wikipedia article for AARD code explains the source:

> The name was derived from Microsoft programmer Aaron R. Reynolds (1955–2008),[7] who used "AARD" to sign his work; "AARD" was found in the machine code of the installer.

According to Wikipedia: " AARD code was originally discovered by Geoff Chappell on 17 April 1992 and then further analyzed and documented in a joint effort with Andrew Schulman.[2][3][4][5][6] The name was derived from Microsoft programmer Aaron R. Reynolds (1955–2008),[7] who used "AARD" to sign his work; "AARD" was found in the machine code of the installer"

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....