Green’s Dictionary of Slang

1. to die.

1968		L. Wolf Voices from the Love Generation 15: You can’t drop out, not even with suicide [...] You’d reincarnate.
1995		Francis-Jackson Official Dancehall Dict. 15: Drop out dying suddenly or unexpectedly, especially under tragic circumstances: u. John drop out las’ week, star.

2. to dismiss, to get rid of someone.

1974		G.F. Newman You Flash Bastard 169: You hungry bastard – you must’ve earnt more than enough. Drop him right out.
1978		S. Longstreet Straw Boss (1979) 212: If they ever did get together, she’d tell Mike, ‘Drop out, we’re making a baby’.
2000		J.J. Connolly Layer Cake 158: This bottle next door reckon someone give him two grand in readies to drop the bird out.
2011		J.J. Connolly Viva La Madness 41: Eve’s dropped him right out, not even a letter, just stopped goin to see him.