Technically helium is not toxic, but if you inhale too much of it it can displace the oxygen in your lungs and cause you to pass out. In an extreme circumstance it might could cause death.
Okay, I’ll shut up. I’m not one that has to keep talkin’. Some fellas just have to keep their mouths flappin’, but not me! I was brought up right, my pa used to tell me “shut up” and I’d shut up! I wouldn’t say nothin’! One time, darn-near starved to death — Wouldn’t tell him I was hungry!
A-moo-sing!