Hey there,
Firstly, as a couple of commenters have established, the specific dun dun DUNNNN OP was thinking of comes from this 1984 album of stock music cues by the composer Dick Walter - specifically the track titled 'Shock Horror (A)'. However, the expectation of AskHistorians is for in-depth and comprehensive answers - we want to see an explanation of the history of music cues in film and previous media (theatre, opera, etc) and where 'Shock Horror (A)' fits into that history, and how similar it is to previous cues.
Additionally, if you want to be reminded of this thread in a day, click here to PM Remindmebot.
Secondly, the usual spiel: if you've come to the thread and are wondering why the comments have been removed, the reason is that, on /r/AskHistorians, we'd rather have no answer than a thread cluttered with bad answers, jokes, and people saying "where are all the comments?". By removing the short, quick, bad answers that would otherwise crowd them out, the well-researched in-depth answers (that take people time to research and write) are more likely to be seen (see this graph for more detail).
This heavy moderation works: we have found that it takes an average of 9 hours for a good answer to appear on a popular thread - properly researching and writing an answer takes time - and that 90%+ of popular threads get an answer. Additionally, it's late at night on the East Coast of the US at the moment, which means that plenty of the historians interested in this topic might already be asleep. The last time we did a survey, 75% of /r/AskHistorians subscribers approved of our moderation, while another 5% thought we should be stricter (and 15% said they didn't care).
In other words, patience, good people. If you want to be reminded to look at this thread later, please see this really awesome Roundtable post for a list of ways. And if you're wondering why Reddit never shows you an AskHistorians thread with answers, consider sorting your Reddit home feed by 'Hot' rather than 'Best' - 'Best' seems to give precedence to newer posts (which are less likely to have an answer on this subreddit, of course) and threads you haven't already looked at (e.g., it'll show you something else next time you log in, even if this thread is still getting lots of upvotes because there's an actual answer now).
If you're wondering what's in the 30-something removed top-level comments at the time of writing, well, you're not missing the kind of long detailed answer AskHistorians is famous for. There are some people commenting about removed comments ('in b4 removed lol'). Some people have identified various quite dramatic music cues (without contextualizing them), while others have made jokey answers, or written short answers starting with things like "I would assume..." or "I'm not a historian but...". None of which meets the standards in our subreddit rules. All of these comments get removed on /r/AskHistorians because the huge majority of our subscribers really do want accurate, comprehensive, in-depth historical answers based on good historical practice and high-quality sources. It's amazing how many downvotes and reports an obvious shitpost can attract on a popular thread on /r/AskHistorians within minutes, thanks to our readers (if you see it, report it!)
What makes a good answer on /r/AskHistorians? Well, we want people answering questions to be able to explain not just what the basic facts are according to academic research, but why we know that these basic facts are right, and to put those basic facts into context. This is why we encourage the use of primary and secondary sources in answering questions, rather than tertiary sources like Wikipedia, podcasts and textbooks.
Unfortunately, the downside of encouraging in-depth and comprehensive answers is that we have to remove a lot of shitposts and comments wondering what happened to the removed shitposts. The upside, however, is that our contributors consistently post amazing stuff to /r/AskHistorians (which we collate the best of every week in our Sunday Digest), and daily on our Twitter. Alternatively, if you want to discuss history without these constraints, /r/history or /r/askhistory might be more appropriate subreddits for you than /r/AskHistorians.