My new name doesn't have a middle name yet, so I'm accepting suggestions on what I could adopt that'd break as many systems as possible.

Obvious answers:
* null
* an emoji
* U+FFFD �
* half of a unicode surrogate pair
* EICAR
* some kind of prompt injection
* the entirety of DOOM, base64 encoded
* an illegal prime
* the source to decss
* 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0

@foone NMN (to be, the value, "no middle name")
@arrjay @foone NA or NAN also strong contenders in this vein
@arrjay @foone also, since nobody has suggested it, a mundane one: anything bidi

@SnoopJ @arrjay @foone

U+200B (zero width space)