Shrek is filled with helium

Not that it would have any chance either but it would be twice as effective if it was hydrogen. That means Shrek may also be able to ignite his breath like a dragon.

I’m just imagining it going like:
“What are you doing *ignites breath* IN MAH SWAMP?”

But that would mean that fionas breath is also helium. She blows up a snake and made a "balloon animal"

Science Easter egg in Shrek. I love it