Today, out of boredom, I was playing my lowbie Blood Elf hunter alt.
I was outside of Rachet, and figured what the hell, I'm going to tame her a pet lion. I tamed kitty, hearthed home, and then went about Silvermoon, and was smelting some ore when...my male lion did his yawning idle animation...and when he opened his mouth, he actually ROARED.
Everytime he idles, yawns, and opens his mouth, he roars now. I thought it was totally neat (I've tamed lions before, they never roared before).
Sadly enough, my Springpaw Cub doesn't roar though.
The lion I tamed was a Savannah Prowler, if I remember correctly, if anyone else wants to test it out.