What does IWBUMS stand for?

[Vandelay]

I see the term IWBUMS plastered here and there as it relates to PZ, but I don't see it defined anywhere. Even Googling it only turns up references to PZ, but still no definition.

[Dracon]

I
W(ill)
B(ack)
U(p=
M(y)
S(ave)

Its basically the beta builds you can register for.
On how to do that that is always explained in the links the devs provide when first announcing a bigger beta build.

[Freeasabird🕊]

Eeew Bums XP

[itslikethis]

Ignorant
Whales
Blast
Unusual
Martian
Sounds
?