This is just a guide for the collectibles in Borderlands GOTY edition (Panties, Fish in a bag, Pizza, Bobbleheads, Oil cans and 3D Glasses) which I noticed that the guide wasn’t really up to date/efficient as it could be. I spent 30 minutes doing this farming strategy and received (I know that its RNG but just citing what I got) 11 Pairs of Pink Panties, 12 Fish in a bag, 7 Slices of Pizza, 4 Bobbleheads, 9 Oil cans and 11 pairs of 3D Glasses.
The strategy is farming Minac but its more refined (still active farming), it requires you to have a shotgun that regens ammo plus another shotgun of your choice (I chose a SES shotgun (ZPR630.3 Fatal Crux) due to its larger mag size, high fire rate and its legendary ability) but you could use any gun also as it has a high damage per hit plus high fire rate. Also I had the shotgun skill maxed at 50 for increased damage, faster reload speed and higher rate of fire.
What to do:
Select the character you want to play as (I was a siren spec’d with Girl power (regens shields after a kill), Phoenix (Killing an enemy causes you to do fire damage and not make your shots count (25% chance to save ammo)), Quicksilver (increased fire rate), Slayer (critical damage), Enforcer (increased accuracy and bullet damage after a kill) and high velocity (increase bullet damage and bullet velocity) and select play through 1. Afterwards run through Wayward Pass and get to the final boss fight. Once you reach the boss destroy all of the turrets (3 on each side, 2 on the back and 1 missile turret on the front) and proceed to farm the claptraps coming from the front of Minac. I just swapped between my SES shotgun and my ammo regen shotgun when needed.
After a fair amount of time you should be able to get all the collectibles using this strategy.
This is my first guide so if theres anything I missed or left out or you have a way to refine it more and use mine as a template, please feel free to comment.