I'm frequently on the road while attending meetings via my cell, usually with wired earbuds (not via the vehicle's bluetooth mic). Of course, they get to hear the "blinkers", as the 1st gen GMC/Chev Canyon/Colorado has a fairly loud "blinker" noise. As the signaling is done by the computer, there is no mechanical flasher to provide the noise.
I've been told more than once that my blinker fluid is low because the clicking is so loud! Thus, that's become the running joke - they know I'm on the road when they can hear the blinker fluid is low.
We blame one of our colleagues; he helped design the GM flasher module while he was employed at Motorola in the late 90's/early 00's. He claims it wasn't intentional; but we think it was designed that way to bolster sales of blinker fluid after the units aged a few years. B^)