Scribblenauts is a puzzle game where you create objects to help you solve the puzzle by simply typing in the word. Type "cat" and you'll conjure a cat in the level. Type "keyboard" and you'll conjure a keyboard. Type "keyboard cat" and... yeah, you get the picture.
I began in the sandbox mode, a themed but empty level with no puzzles. Here you can experiment by typing in random words and seeing what happens. I tried a few of the words you'd suggested.
"BFG" didn't work. The Warner rep I was with suggested "Big Friendly Giant" instead, which did work. However I suspect it just picked up on the word "Giant". "Chuck Norris" failed me as well since no real people are in the game.
"Clinical Neuropsychologist" did work, assuming your idea of a clinical neuropsychologist is an old guy with receding white hair. "Spatula", "Penguin", "Butter", "Parasol" and "Black hole" all worked too. The latter sucked the penguin and neuropsychologist to their doom.
I trashed everything from the sandbox level and started again. This time I added a pirate then a monkey, both of whom were happy to wander around next to me. Next I added a ninja who immediately attacked and was killed by the pirate. The monkey picked up the ninja's throwing star. Then I added a zombie and a robot. The zombie attacked the monkey, but lost! The surviving pirate, monkey and robot were content to exist peacefully, although the latter seem rather confused by the whole thing.
I trashed these guys and continued moving through your list of words. "Gamer" gave me a kid in a black t-shirt. "Axolotl" gave me a frog - close enough, I figure. "Slinky" didn't work, presumably because it's a trademarked name. "C4" doesn't work because only letters are allowed. "Plastic explosive", however, did work, handing me a remote controlled charge distinct from the spherical bomb you see from typing just "Explosive".
"Chewing gum" gave me a pre-chewed wad of stickiness. "Propeller hat" gave me a regular hat. Slightly disappointed, yet undeterred, I put the hat on my avatar. I then attached the chewing gum to the hat. Certain objects can be stuck on or attached to others, you see. I typed in "Propeller" and attached the propeller to the chewing gum stuck to my hat.
My avatar immediately flew into the air. Yes, Scribblenauts lets you make your own propeller hat.
I typed "Corpse" and a zombie appeared. This time though it wasn't walking around, preferring instead to lie limply on the ground. The Warner rep suggested we add some "Lightning". It struck the corpse and turned it into the shambling zombie I'd seen earlier. It's also possible to attach a wire between a corpse and a car battery to raise the dead.
Lastly, riffing on the theme of mortality, I entered "Grim Reaper" and watched as Death himself chased my avatar around the screen. Thinking quickly, I typed "Spartan" and a near-naked warrior appeared. His spear was no match for sickle, however, so I added a second then a third and then a fourth Spartan in quick succession. By the end of the battle, only one Spartan remained standing.
So, there you go, it takes an army of four Spartans to defeat death.