fwustwated

It is a derivative of "frustrated" (just replacing the "r" with "w"). It is intended to sound cute; just like other kinds of babytalk.

It can be used when either playing as a Small/Little (in the kink sense) or if someone was trying to imply that the cause of the frustration isn't that much of a big deal, kinda diminishing the importance of it, if you will.

Can also be spelled "Fwustrated" or "Frustwated"