How hard is it to sing on-key? For many people, it can’t be done. I’ve sat in restaurants and listened to people absolutely murder the “Happy Birthday” tune — and singing “Happy Birthday” is about as easy as it gets. It’s not just hitting notes — you also have to slide into them, sustain them. Wake me up at 4 in the morning and I’ll sing “Your Smiling Face” perfectly in terms of phrasing and hitting notes. Same thing with “Be-Bop Baby.”