spew one's guts (out)
1. Sl. to empty one's stomach; to vomit. Fred is spewing his guts out because of that lousy fish you served. He's spewing his guts because he has the flu.
2. Sl. to tell everything that one knows; to confess everything. (Underworld.) Lefty was sitting there in the police station spewing his guts out about the bank job. If he really is spewing his guts, the mob will cancel his Christmas.