"They will kill you!"
When I was a little girl and we lived for part of the year in Vero Beach, we viewed Portuguese men o' war as jelly terrorists. Lying in wait on the beach after the tide receded, they would whip their 50-foot long tentacles into the air and snap them around your legs, causing you to gasp for breath and writhe in pain as you succumbed to a slow and tortuous end.
I don't know how we expected them to consume us, or why we thought that they would have any interest in trying. I suppose that logic is not a component of childhood drama.
These days, I view them with a good deal more equanimity.