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Related to blab out: blab around
To talk about or reveal a private or secret matter. A noun can be used between "blab" and "out." I can't believe you blabbed out the plans for her surprise party right to her face! Don't tell your little brother anything you want to keep secret because he'll definitely blab it out.
blab something out
Inf. to speak out freely about something that is a secret. Don't just blab it out! Don't blab out the names of the people who were there!