Got this from my uncle, thought it was sort of cute:

Use the third letter of your first name to determine your new first name:

a = poopsie b = lumpy c = buttercup
d = cookie e = crusty f = greasy
g = fluffy h = cheeseball i = chim-chim
j = stinky k = flunky l = bootie
m = pinky n = zippy o = goober
p = doofus q = slimy r = loopy
s = snotty t = tootie u = dorkey
v = queezy w = oprah x = skipper
y = dinky z = zsa-zsa

Use the second letter of your last name to determine the first half of your new last name:

a = apple b = toilet c = giggle
d = burger e = girdle f = barf
g = lizard h = waffle i = cootie
j = monkey k = potty l = liver
m = banana n = rhino o = bubble
p = hamster q = toad r = gizzard
s = pizza t = gerbil u = chicken
v = pickle w = chuckle x = tofu
y = goat z = stinker

Use the fourth letter of your last name to determine the second half of your
new last name:

a = head b = mouth c = face
d = nose e = tush f = breath
g = pants h = shorts i = sneakers
j = honker k = butt l = brains
m = tushie n = biscuits o = hiney
p = chunks q = toes r = buns
s = fanny t = sniffer u = sprinkles
v = kisser w = squirt x = humperdinck
y = brains z = juice

Thus, for example, George W. Bush’s new name is Goober Chickenshorts. William Jefferson Clinton is Bootie Liverbiscuits.