dummy

A trial or practice version of an event, done to prepare for (and mitigate any possible problems during) the real thing. Primarily heard in UK, Australia. Let's do a couple dummy runs of your speech so you feel totally comfortable with it for tomorrow's ceremony.

A childish, angry overreaction to a negative situation or outcome; a display of bad temper, likened to a temper tantrum of a child. "Dummy" here refers to the British term for the device used to soothe babies (called a pacifier in the US or a soother elsewhere), which they may spit out when in the middle of a tantrum. Primarily heard in UK, Australia. John had a dummy spit when I told him I'd sold his old comic book collection.

To have a childish overreaction or angry outburst to a negative situation or outcome; to act in a bad-tempered manner, likened to a temper tantrum of a child. "Dummy" here refers to a plastic teat used to soothe teething infants (also called a "pacifier" in the U.S. or a "soother" elsewhere), which they may spit when in the middle of a tantrum. Primarily heard in Australia. John spat the dummy when I told him I'd sold his old comic book collection. Don't go spitting out the dummy just because Cheryl got the promotion instead of you.

Sl. to refuse to talk. Jill dummied up when they got her into the station. John dummied up right away when the police arrived.

an occasion when you practise doing something to make sure there will be no problems when you really do it We decided to do a dry run at the church the day before the wedding. We'd better have a couple of dummy runs before we do the real thing.