From the Netherlands, never heard of it. Living in germany four years now, now that you remind me, I had to dig deep in my memory (at first I thought it might mean SS somehow), but yeah someone once mentioned it's the 8th character of the alphabet and so if you associate HH with the 2nd world war, you can read something into it. Most definitely not among the first associations for me, and believe me we had enough WW2 material in school (including kids that use hitler stuff to be funny). Perhaps 88 is specifically edgy in german high schools or so? I bet if you look at other cultures, it'll mean donkey balls or some such somewhere. I've also heard a german laugh about a 1312 license plate which I'd never think to associate with alphabet offsets in my life. Would be "ieiz" or "lelz" for me, if anything.

TL;DR very far fetched and a bit pointless to go looking for these non-obvious alternative meanings, in my opinion