Drop dead money
The term comes from a character in the James Clavell novel, “Taipan”. A character in that novel, a lady executive has the objective to have “drop dead money”. The “drop dead money” is that amount of money that she calculates she needs so that she would have the freedom and the luxury to tell anyone to “drop dead” without worrying about her financial security.
To accumulate this “drop dead” money she had been working hard for a businessman who had promised her a bonus equivalent to the “drop dead money” if she could pull off a successful acquisition.