I came across this expression here, and it said
Johnny Depp Has a Jolly Old Time, But Pirates Is Yo-Ho-Hum
My Robert & Collins Dictionary says
deep-six ** transitive verb US
= throw out : balancer **
= kill : liquider **
The The Free Dictionary by Farlex says
tr.v. deep-sixed, deep-six·ing, deep-six·es Slang
1. To toss overboard.
2. To toss out; get rid of: deep-sixed the incriminating papers.
A pretty colourful and imaginative expression. You can imagine Johnny Depp, or maybe rather the movie being tossed overboard, never to be heard of again 😉