What if you agreed to only speak in anger while helium was in effect?
One big drag of helium then...go.
Or argue theatrically, with full drama, opera or Shakespearian grandiosity.
Accent, cartoon or even singing arguments.
Admittedly this would work better if you both stand right out of reach...Just in case a violent/wild urge comes about when your partner is laughing at you hysterically.
Inspired from the movie – The 5 year Engagement.
They were Elmo and the Cookie Monster.