It's One's Funeral Meaning
(idiomatic) One's decisions or actions will bring undesirable consequences only on oneself.
Example: 1928, D H Lawrence, Lady Chatterley's lover
He can make as many empty tubes and corrugations out of me as he likes. It's his funeral.
1936, Caroline Slade, Sterile sun
And then having the nerve to pray to God. It's her pimp, if she wants to do it it's her funeral.
1946, Winston Clewes, Sweet river in the morning
"Well, it's your funeral," Charlie said. "If you like it, I should worry." "Who says I like it?" the other lad said, angrily. "What else can I do?"