Some 20 years ago, back when getting your own phone landline in Brazil was a small luxury, a friend of mine finally bought hers and was wrapped.
I thought it would be the perfect opportunity for a little practical joke and called her - probably one of her first phone calls from the new phone!
I pretended that I was from the phone company and wanted to run some quality tests on her line. This is how we took it from here.
"Hello madam, I'm from the telephone company and we'd like to run some tests on your new line. Could you shout into the speaker, please?"
With little hesitation, she yelled a shy "Aaahhh"
"A bit louder,please Mam."
"Great, thank you. Now, could you please whistle?"
She once more obeyed.
"Now could blow a bit?"
Never suspecting the methods to be unusual or from fear of being backwards and not used to these modern things, she kept doing the requested exercises.
Even though my laughter probably gave it away, the penny finally dropped when I asked her to try once more to see if she could blow out the candle on the other side of the line.
:Click: (hang up)
She wouldn't talk to me (even on the phone) for a long time after that episode!