Well, there's a reason no one can remember the saying...
Red on yellow will kill a fellow, but red on black is a friend of Jack.
Red on yellow, deadly fellow; Red on black, venom lack.
Red and yellow will kill you fellow; Red and black is friend Jack.
Red on yellow, kill a fellow. Red on black, you're alright Jack.
Red next to black is a friend of Jack; red next to yellow will kill a fellow.
Red to yellow, kill a fellow. Red to black, venom lack.
If red touches black, you're okay Jack; if red touches yellow, you're a dead fellow.
Red next to black, you can pat him on the back; red next to yellow, he can kill a fellow.
Red next to black, venom I lack; red next to yellow, run away fellow.
Red and black, friend of Jack; red and yellow kill a fellow.
Red touches yellow, Not a nice fellow; if red touches black, good friend of jack.
Red touch yellow, kill a fellow; red touch black, you're okay Jack.
Red touch black, good for Jack; red touch yellow, kill a fellow.
Yellow and red, you are dead; black and white you're allright.
http://en.wikipedia.org/wiki/Milk_snake
They're not that hard to distinguish them visually if you familiarize yourself a little.