Spooner lost

When my daughter was young I coined an acronym for the pre-bed activities. It is PTTB which stands for pyjamas, toilet, teeth, bed.

Ok, its an initialism not an acronym but who gives a fuck?

In any case, for some reason neither of us could ever get this acronym right. It variably came out as PTBB, PPTB etc.

So I wonder is there a descriptor for Spoonerisms of acronyms and initialisms? I know the answer to that one already.