Prince 
"Dirty Mind"
outtakes 1980 - 1982 & Rehearsal 1984
various > silver bootleg CD > EAC > flac > CDR

STUDIO OUTTAKES
1. VIBRATOR (DIALOGUE 1)   
2. VIBRATOR (DIALOGUE 2)   
3. VIBRATOR   
4. CLIMAX   
5. LISA
REHEARSAL : 1984
6. BILLY'S SUNGLASSES


'Billy's Sunglasses', being part of Purple Rush, Vol 1, disc 3, I found this info on TheDataBank:
"Billy's Sunglasses is one of the lengthiest loose jams in circulation and revolves around the seemingly improvised lyrics of "Billy, where you get those glasses" in reference to Billy Spark's funky white rims. The rehearsal lasts for 47 minutes yet 'Billy's Sunglasses' is itself 40 minutes long, and whilst I can perfectly understand it not appealing to the majority of listeners due to it's repetitive nature, there are some inspired guitar solo's played throughout. The remainder of the rehearsal consists of a quick instrumental run through of 'Strange Relationship' with Prince calling out the key changes to the band."
"There are a small number of glitches during 'Billy's Sunglasses'"