WORKING CHEAT FOR PSP!
Basically, go to the Perks purchase screen (not the My Sim page but the Buy Perks menu) and press L+R+Square. A little Whoo-Hoo heart will appear on the buy perks and you can buy it for nothing.
In the game press square and left/right to find the perk. Select it and a screen will appear saying....
"Activate" and "Fill sanity, reset urgencies, gain $1000" and a list of skills you can advance. Select what you want and press 'activate'. Press triangle to get back to the normal screen and everything will work.
I promise you this works. If it doesn't, feel free to ask me about it.
More tricks, tips and cheats for this game are right here - The Sims 2 cheats
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