The (polite) Four Letter Word Game

bing

http://www.finedictionary.com/Bing.html

zing

zinc

zine

nide

dune

dunt

http://www.finedictionary.com/Dunt.html

stud

dusk

sued

feud :gun:

duet

suet

guts

glut

lung

gull

gill

will

lily

:bouquet: