To put all your feelings out on the line in an undignified or embarrassing manner. To reveal embarrassing secrets about your wants/hopes/dreams. To let your mask down.
You really like to spill your purse when you get drunk.
Mike spilled his purse out proposing to Donna, and she still turned him down.
To reveal the truth about something, usually in a gossip-like manner. Gracefully derived from the common phrase "Spill the Beans". Not to be confused with "Spill the Tea", an extremely racist appropriation of "Spill the Beans" made common by Gen Z neo-nazis in 2008
Edward Snowden sure did spill the ketchup when he leaked all those classified government secrets