YOU KNOW IT MAKES SENSE... in some way.
It probably sounded something like this -> [link]
But, thinking more about it, I imagine Pinkie's "HONK" sounding more like Spongebob's wake-up alarm clock. I just can't seem to find it anywhere. :C
Discord, Pinkie Pie and Fluttershy © MLP FiM/ Lauren Faust
EDIT: aw crap, totally forgot his beard in the second panel ._.;