I am 100% sure your friends are confusing "Don't worry, be happy" with "Three little birds". Don't worry about a ting, cuz every little ting is gonna be alright, rize up this mornin, smile with the rizin sun, three little birds, sit by my doorstep, singin a sweet song, a melodys pure and true, singin "This is my message to you-hoo-hoo !