What some slang words for helium?

There aren't really any widely used slang words for helium specifically. It's a fairly technical term, and slang usually arises from more common or everyday objects or experiences.

However, you could *use existing slang words* that relate to the *effects* of helium:

* "Laughing gas" is slang for nitrous oxide, which has similar effects to helium inhalation (making your voice high-pitched and causing laughter).

* "Buzz" is a general term for a feeling of lightheadedness or excitement, which helium inhalation can sometimes cause.

If you're talking about the use of helium in balloons, you could use slang words like:

* "Floaty stuff" (referring to the gas making the balloons rise)

* "Party gas" (referring to the use of helium in celebrations)

Keep in mind that inhaling helium can be dangerous, so it's best to avoid using slang terms that encourage this behavior.