Not so much Johnny Depp, probably would get in trouble for that
Might be able to get away with something like "Captain Jake Swallow" or something though ^^ (It's referencing Jack Sparrow, for the record)
A fun little extra Firefly reference for Batrider could be calling him "MalWash"
Also used to call Brewmaster the "Sad Panda", since he's such a drunk
Centaur could be Big Beefy, or Fatty McBeefcakes
Tiny could be Rocky the Hulking Behemouth, or Grawp, or Rolling Thunder, or Wheels
or F***** Slow as S***, as I lovingly refer to him as sometimes.
Could call CM Fridgcicle the Ice Princess, or Frigid B****, that's what I call her sometimes lol