"Ghoti" is an artificial example that doesn't actually work if you account for the way positioning affects pronunciation. Pull up a list of words that start with "gh": none of them (unless "ghoti" itself is on the list) start with an /f/ sound. You'll find the same for words ending in "ti" and the /ʃ/ sound.

I recommend asking people how "ough" is pronounced instead. Cough, bough, though, thought, through, thorough, hiccough--enough!