I love that the list of things that substance reacts violently to is “test engineers”. 
Nitrogen narcosis. I have heard it described as like being really drunk. It certainly impairs judgment and you can find examples of people dying because of it.
Like pilots needing to be very serious about the job of flying hundreds of feet in the air divers need to be equally serious when hundreds of feet underwater. Both are unforgiving places to make mistakes. Impaired judgement is no bueno.
That would largely be true of helium, too.
@Brayne_Ded and @Deeg
Both Nitrogen and Helium bags are advocated by the supporters of Euthanasia.
Balloons don’t really impact the shortage, accounting for about 10% of all helium use. Cite:
A while back I wondered why we don’t use nitrogen for capital punishment. It sounds like a painless way to go.
Actually, several things are suitable for “insert gas asphyxiation”. In this context , “inert” means inert with respect to your respiratory processes, not actually chemically inert.
All the noble gases should work, as well as a plethora of others. That wiki article lists argon, helium, nitrogen and methane as examples. Argon is the most plentiful of the noble gases (actually a larger percentage of the atmosphere than carbon dioxide - almost 1%). You could probably even use radon - if you’re going to die, it hardly matters that you get radiation poisoning while doing it. If anybody is administering it to you, they’ve got some complications in handling it, of course. And I wonder if your corpse would present a radiation hazard.
Yeah, it should probably be used for capital punishment.
Xenon is used for general anaesthesia. I don’t know if there is a shortage, but it is not cheap and apparently not available in every random clinic or surgery.
Definitely not a radiation hazard. Radon doesn’t combine with anything under normal circumstances, so there won’t be significant amounts on or in the corpse. Maybe some trace amounts trapped in the clothing or lungs or whatever. Not enough to be a hazard.
If you have your parties on Venus, the nitrogen can act as a suitable lifting gas.
Yeah, but what would you make the balloons out of that could take the heat?
I do like that that was the only flaw you saw in my plan.
But, you can have you parties up in the clouds, 50 km or so up, and it should be a nice comfy weather.
Steel foil would work, even down at the surface. The atmosphere is so dense my WAG is the weight wouldn’t be an issue if you kept the foil thin.
You can make foil out of steel? Huh. What a time to be alive.
Well, it would work if it didn’t rain hot sulfuric acid on Venus. But I’m pretty sure that would dissolve almost any metal foil in short order. Maybe you could coat it with a thin layer of gold.
Crap! A 100 million mile trip and I plumb forgot about the acid! Better luck next time.
This is a genuinely hard problem. There’s so little overlap between Earth surface and Venusian surface conditions that all our hip-pocket ideas fail to account for something.
It’s not a party until it rains sulphuric acid! Come on, man, didn’t you learn anything in college? 
Just have your parties in a pool. A ballon filled with ANY gas will float - even Avgas.
This past summer from my farmer in-laws I learned that the metal bracket on the bottom of these lanterns will stop a hay chopper dead in its tracks. The last few versions of state-of-the-art farm equipment contain metal detectors. He said cruising around the fields going from 25mph to nothing because of an old arrow is not fun. There is more than enough metal here to be detected. And find it they must. It is still inside the chopper, not blown into the wagon/trailer yet.
FTR, this is what happens when one inhales noble gases.
ETA: I had to Google “frobscottle.” It’s from a Roald Dahl book; it’s a carbonated drink where the bubbles sank.