Adrenaline Rush

Adrenaline Rush is a Fallout 2, Fallout Tactics and Lionheart Perk.

Fallout 2 and Fallout Tactics
This will increase your Strength by 1 when you drop below 50% of your max hit points.

Lionheart
You will gain +1 to Agility and +20 evasion if your hit points drop below half of their maximum and an additional +1 to Agility and +10 evasion, +1 melee dmg if they drop below 25%.

Fallout 3
The perk, Nerd Rage!, from Fallout 3, is similar to, both, the image and benefit of this perk.