Mutate!

 is a Fallout, Fallout 2 and Fallout Tactics perk.

The radiation of the wasteland has changed you! One of your Traits has mutated into something else... Notes:
 * If you chose only one Trait when creating the character, you can only exchange it for a new one. You cannot fill the empty slot.
 * In unpatched Fallout 1, you could exchange Gifted for another Trait and still keep the Character Points.
 * While minimally useful in Fallout and Fallout 2, Mutate! is a reasonable perk in Fallout Tactics, where it can be used remove unwanted Traits from NPC squad members.
 * In Fallout Tactics, Mutate! can be used to give NPC party members a trait when they have none already.
 * The image for this perk is likely a reference to Marvel Comics' Dr. Bruce Banner/The Hulk, a mutant.

See also: Mutations and their causes.