Why 'Plunge'? I'm sure most of us could think of perhaps more 'fitting' words beginning with
'P', though I doubt the moderators would allow their use.

I think there a simple mix-up here.
I've observed that there is a person using the same names posting ESL teaching advice on the International Sex Guide in the China section.
The moderators there are upset by the off-topic posts. Teaching tips on a prostitution website is apparently unacceptable.