Crazy Dave

Crazy Dave is your average crazy neighbor who wears a pot on his head, presumably to protect his brains from being eaten, and it appears to work, as the Zombies didn't eat them after he was grabbed.

During Adventure Mode, Crazy Dave serves as a sort of narrator, introducing you to certain levels and explaining some of the mini-games through speech bubbles, as his speech sounds like nothing but babbling. However, and is later abducted by a Bungee Zombie on level 5-10 right before he can tell you Dr. Zomboss's weakness.

He also has a shop called Crazy Dave's Twiddydinkies that he runs from the back of his car, once you locate his car keys. He sells several upgrades to plants, your pool and roof, and your Zen Garden. Purchasing from Crazy Dave is also the only way to increase your available plant slots to 10.

When re-playing Adventure Mode, Crazy Dave will pick 3 of your plants for you each level, which you can't switch out, but quitting and reloading the game makes him choose three different ones.

Things you can purchase from Crazy Dave's Twiddydinkies

 * Extra Seed Slot (number 7) - $750 (can be purchased earlier if the player has enough money at the end of a level)
 * Extra Seed Slot (number 8) - $5,000 (can be purchased earlier if the player has enough money at the end of a level and the previous seed slot has been purchased)
 * Extra Seed Slot (number 9) - $20,000 (can be purchased earlier if the player has enough money at the end of a level and the previous seed slot has been purchased)
 * Extra Seed Slot (number 10) - $80,000 (can be purchased earlier if the player has enough money at the end of a level and the previous seed slot has been purchased)
 * Pool Cleaner (last line of defense for your Pool) - $1,000
 * Garden Rake (semi-reusable lawn defense) - $200
 * Roof Cleaner (last line of defense for your Roof) - $3,000
 * Gatling Pea (Upgrade of the Repeater) - $5,000
 * Twin Sunflower (Upgrade of the Sunflower) - $5,000
 * Gloom-shroom (Upgrade of the Fume-shroom) - $7,500
 * Cattail (Upgrade of the Lily Pad) - $10,000
 * Spikerock (Upgrade of the Spikeweed) - $7,500
 * Gold Magnet (Upgrade of the Magnet-shroom) - $3,000
 * Winter Melon (Upgrade of the Melon-pult) - $10,000
 * Cob Cannon (Upgrade of the Kernel-pult) - $20,000
 * Imitater (Allows you to have two of the same seed during a level) - $30,000
 * Wall-nut First Aid (Allows you to replace Wall-nuts, Tall-nuts and Pumpkins without digging them up first) - $2,000
 * Marigold Sprout (You can purchase up to 3 of these every calendar day to place in your Zen Garden) - $2,500
 * Golden Watering Can (Allows you to water up to four plants at a time) - $10,000
 * Fertilizer (Necessary to grow plants to full size) - $750 for 5, max of 20 can be purchased at one time
 * Bug Spray (Necessary for happy plants) - $1,000 for 5, max of 20 can be purchased at one time
 * Phonograph (Necessary for happy plants) - $15,000
 * Gardening Glove (Allows you to move plants around in the Zen Garden) - $1,000
 * Mushroom Garden (Allows you to care for and mature Mushrooms) - $30,000
 * Aquarium Garden (Allows you to care for and mature Aquatic Plants) - $30,000
 * Wheel Barrow (Allows you to move your plants from one Zen Garden to another) - $200
 * Stinky the Snail (Collects coins for you in the main Zen Garden) - $3,000
 * Tree of Wisdom (Grow the tree to learn valuable secrets about the game) - $10,000
 * Tree Food (Necessary to grow the Tree of Wisdom) - $2,500, max of 10 can be purchased at one time

Crazy Dave will buy a Magic Taco from you for $1000 (found on level 4-4 of the first play-through of Adventure mode). He will also reward you with two Marigolds when you unlock the Zen Garden.

Pop-culture Reference
Crazy Dave is probably based on a series of commercials in the 70's and 80's for a consumer electronics company [1] in the northeastern United States. Jerry Carroll, a popular radio disc jockey, played the frenetic host with the memorable slogan, "Crazy Eddie, his prices are IN-SA-A-A-A-A-ANE!". It should be noted that Jerry did not actually play Crazy Eddie, but always referred to him in the third person.

Trivia

 * In the credits, the song Zombies on Your Lawn, Crazy Dave is being held upside-down (by the Bungee Zombie which abducted him at the beginning of level 5-10 before the boss battle against Dr. Zomboss), but his pot doesn't fall off his head.
 * There are only two times it is ever seen off his head in the entire game. Once is when he says "BECAUSE I'M CRAAAAAAAZY!" while introcuding level 1-5. His pot flies up in the air, does a flip, and falls back on his head. When he is first kidnapped by the Bungee Zombie, his pot is seen tumbling to the ground.
 * If you stay in his shop long enough, he might say "Act now! I'm CRAAAAAAAAAAZY!" though his pot will not come off his head.
 * If you hang around long enough in his shop without doing anything, he might say "I eat food off the floor!".