Psycho

Psycho is a drug in Fallout, Fallout 2, Fallout 3, Fallout Tactics and the cancelled Fallout: Brotherhood of Steel 2.

Background
Composed of strange, unknown chemicals of military origin, the Psycho comes with its own unique delivery system. It was designed at the orders of General Constantine Chase and is supposed to increase the combat potential of a soldier, whilst dampening higher mental functions, making for fearless, but uncontrollable troops.

Psycho appears to be a form of injected drug, which, considering the large serum canister next to the needle, suggests that large quantities are needed to produce the effects.

Fallout, Fallout 2 and Fallout Tactics
Psycho has another beneficial effect not intended by the programmers. When taken, it reduces Intelligence by 3. This can be exploited to boost your skill points. First, raise a skill to the point it needs two skill points to be increased, then level up.

When you level up, take two to reduce your Intelligence greatly. This will correspondingly lower your skills involving Intelligence (Science, Repair, Outdoorsman, Doctor, etc). Now allocate your skill points to the skill you want raised - since the skill's value has been lowered, it will take only one skill point to do so. Then rest for a few hours. When the Psycho wears off, Intelligence will be restored, and the skill will be given a significant boost. This is particularly useful for getting a 121% Science skill to recruit Skynet without taking Mentats or wasting too many skill points.

Locations
Psycho is very common in the capital wasteland, and sometimes sold secretly by shady merchants. There are around 60 in guaranteed locations.
 * At least one dose can be found in Silver's house, slightly northeast of Vault 101
 * Around 3-4 doses can be found in the Super Duper Mart
 * Is frequently found in Raider establishments
 * It is sold by Doc Hoff, Cindy Cantelli, Ahzrukhal, Leo Stahl and sometimes by doctors.
 * Three can be stolen from Rivet City's chem shop, A Quick Fix.
 * Four can be stolen from Cantelli's Room in Rivet City.
 * Can be found on the dead bodies of Wastelanders.
 * Can be found on the corpses of Talon Company Merc.

bugs
Sometimes the damage counter in the pip-boy 3000 will partially be affected by the 25% damage bonus, making weapons look more effective than they are in reality. With the other damage modifying perks, Ghoul Ecology and Superior defender from Point Lookout, unlucky players can get the Xuanlong Assault Rifle standard 64 damage titled so much that it can show up to 180 damage on the pip boy. (Confirmed on 360)