Yorker
yapping
yearning
Yavapai
young/youthful/youthsome
yellow (as in cowardly)
zany,zealous,zenophobic,zebrine,zygotic,zebroid,zesty,zestless,zestful,zincic,zincoid,zincous,zincy,zingy,zippy,zonary,zonzte,zonated,zoogenic,zoologic,zoonal and zooty
yes-man
yokel
yummy
yielding
yawner
yorker
yearner
yahoo
yodeler
yeller
yelper
yeomanlike/yeomanly
yowzer
yucky