One thing that has pretty much disappeared since the arrival of CD and now downloads is the mad stuff that used to get done with records - you know the kind of thing: strange noises in locked grooves, writing in the dead wax area near the label, records with double (parallel) grooves, all that sort of stuff.
It was just another one of the things that made record buying fun.  I miss it.

Some classics:
Side two of the 12" single of 'Pop Misic' by M had a double groove so you didn't know which track was going to play until it actually started to play.
Porky Prime Cuts - George 'Porky' Peckham used to sign the dead wax with 'A Porky Prime Cut' or variations of that.
'Matching Tie & Handkerchief' - the 3 sided record by Monty Python has a locked groove which repeats ' Sorry squire, I scratched the record… I scratched the record… I scratched the record…'


Prize for most wacky I know of goes to 'Pagan Muzak' by Boyd Rice (as NON) - a 7" disc that came in an LP sleeve. Each track (17 of them) had a locked groove but the disc also had an extra spindle hole so that a whole new set of 17 non-concentric tracks could be played. You were also encouraged to play it at 16, 33, 45 and 78 rpm! This gave 500-odd permutations of track choice & obviously needed you to be pretty nifty on your feet if you wanted to hear the whole disc in one session! As the grooves were locked, you could choose the length, pitch and tempo of each track (& presumably vary them at will!)

So despite it only being 7" in diameter, this made it a truly long playing record!  Not very good music, but unusual.  Pinch may love it!