Big Game Huntin' with Jimbo

Visit his shop in the northwest corner of town (beside Skeeter's) and purchase the Hunter's Guide for $5.00. There will be six targets on different locations. You'll obtain the games' unique baits as your quest items. You can report back to Jimbo after taking down the targets to get some useful Weapon Strap-ons and Equipment Patches. Take note that some of the targets can only be accessed as you go through the story and there's one missable target that can only be accessed during one specific quest.

Farm Cow

Head to the ranch and attach the cow bell near the fence to call the cow. Simply hit it with your weapon to defeat it.

Rabid Junkyard Dog

Head east of Kenny's house and you'll find a spot near the trail to the woods where you can put the bait.

Penis Mouse

You need the alien probe tool that you can get from main quest “Alien Abduction” to reach the deeper part of the sewers. The entrance is found in the open manhole outside the news office. While doing the sidequest "Dropping the Kids Off", you'll run across a large, closed tunnel right before the ladder leading to where one of Mr. Hankey's kids, Cornwalis is held captive. There's a destructible wooden plank hiding it so you'll have to destroy it to reveal it.

Open the grate using the switch then climb up the ladder to find the deadend where you can place the bait.

Fruit Bat

You can do this while exploring the whole sewer system. After finding Mr. Hanky's kids during the quest “Dropping the Kids Off”, fully explore the sewer and you'll eventually reach a cavern with a chanting crab person across the chasm. Continue to the right until you find the ladder leading back to the surface. There's a small path leading southwest. Take it and place the bait to Summon the bat.

Mutant Bacteria (Missable)

During the quest “Attack the School”, you'll reach the basement area where the nazi zombie gingers are hanging out. After getting past the hazards, you'll find a door marked as "Boiler Room" to the north, right before you reach the stairs. Enter the room to find several petri dishes and place the bait on the green moss-like thing to trigger the battle.

Barking Spider

Once you've reached 8-bit Canada, head to the northeast in the overworld map to find a large spider web. Just place the bait there to fight the spider.