The secret to quickly stopping hiccups
If you want to stop hiccups, the secret lies in addressing the root cause: your diaphragm. Research shows that the most effective way to disrupt hiccups is by expanding your lungs. To do this, take a deep breath, hold it for as long as you can, then inhale. This technique forces your lungs to expand fully, pushing out any trapped air or muscle twitches in your diaphragm, effectively stopping the hiccups. In addition to deep breathing, you can also try to prevent hiccups before they fully take hold with quick remedies like sipping cold water.
Source
Steger, M., Schneemann, M., & Fox, M. (2015). Systemic review: the pathogenesis and pharmacological treatment of hiccups. Alimentary pharmacology & therapeutics, 42(9), 1037–1050. https://doi.org/10.1111/apt.13374
Additional Reading
https://betterreport.com/how-to-get-rid-of-hiccups/
https://www.health.harvard.edu/staying-healthy/stopping-hiccups
https://www.verywellhealth.com/how-to-get-rid-of-hiccups-7488794