high-pitched whistle sound

Ha-haah! It's funny because it's social commentary...
 

h.p.

Well, now! Who might this book-enthusiast person fellow be, I wonder? He reminds me of someone...

liberating terrors

Oh, no. Not THIS guy again... You know this guy, right? You know who I'm talking about. You've met him. Yeah. Him.                                             ......................Ugh!

No comment. At all.

astronomical phenomenon

Oh, my! Is this an actual PHOTOGRAPH I've posted here? Why, I haven't seen one of those in AGES, etcetera, etcetera. Anyway, yeah: people always ask me "Is it safe to go to the park, Luca? What'll happen if I encounter a gravitational singularity on my walk?" Well, people - this is it. This is what happens. Stay safe out there!
 

 I should clarify: we refer here to the American-English interpretation of the word "pants". You know - trousers.

vapor

 

I suspect this must be one of those locomotors. No way to be sure.