a alien race comes to the earth and it feeds on gum... its planet ran out of gum so it came to earth to get some and finds an alternateive food source, human brains.

So this is what im thinking:
There is only one man left on earth after the apocolipse and it is his dream to have 1 last piece of gum before he dies but a alien race comes to the earth and it feeds on gum and eats it all and then decides to eat the man because the gum is all gone and then need to feed on human flesh, and seeing is the man was the last human, the alien race dies out.