like, I have gone on record many times saying how cute lil moo moos are, but please, consider the following:
lil meow meow
lil oink oink
lil blub blub
lil baa baa
lil honk honk
lil quack quack
lil chirp chirp
lil squeak squeak
lil buzz buzz
lil hiss hiss
lil cluck cluck
or if you want to stretch out the pattern to two syllable sounds:
lil ribbit
lil hee-haw
lil clip clop
lil splish splash
lil trumpet
lil flip flap
lil gobble
and I'm sure there are lots more I'm not thinking of!