Jokes, comic bits, or running jokes in a performance

• A prank or humorous trick

Devices that block the mouth to prevent speech

• Instruments that hold the mouth open in procedures

Rules or orders forbidding discussion of a topic

• Any measure that suppresses free expression

Has a retching or choking reflex

• Reacts with nausea to a taste or smell

Silences someone by blocking speech, physically or by order

• Puts a gag on or enforces a gag order

Biochemistry: glycosaminoglycans, long polysaccharides in tissues

• Plural of the initialism GAG