Here are some more, straight from the original
Fiend Folio:
Assassin Bug → Assassin Pug - Who's a bad dog? You are! Oh, yes you are!
Crabman → Crapman - It's "Mr. Hankey" with legs!
Dark Creeper → Dark Cheeper - A baby chicken with black feathers
Dark Stalker → Dark Talker - So basically just a Goth
Dune Stalker → Dung Stalker - Look out, Mr. Hankey!
Flail Snail → Frail Snail - Its shell is really, really thin
Giant Strider → Giant Stridex - That ought to clear up that acne for good!
Hellcat → Hellocat - "Hello Kitty" when she becomes an adult
Hook Horror → Book Horror - A horrid monster who (gasp) writes in books!
Lava Child → Java Child - All that coffee's going to stunt your growth, kid!
Scarecrow → Sparecrow - For when your original crow flies away and doesn't come back (or worse yet, gets baked in a pie with 23 others)
Shadow Demon → Shadow Lemon - A tasty fruit from the Plane of Shadows
Shocker → Shucker - An "ear seeker" of a different kind, focusing on corn
Volt → Dolt - Okay, this one's just plain dumb!
Xvart → Xfart - The little guy dealt it!
Yellow Musk Zombie → Mellow Musk Zombie - "Dude, chill out! It's not like I'm going to eat your brains or anything!"
Johnathan