I am not sure if these are for the PS2 Matt Hoffman (if this game is on PS2), but here is what I found:
Tony Hawk:- Get all thirty covers and two gold medals in career mode with any character to unlock Tony Hawk on an old girls bike.
Exorcist mode:- Enable the "Big tires" code, then get over 10,000 point to have your rider's head spin on their shoulders.
Warehouse level from Tony Hawk's Pro Skater:- Score a 200,000 combo. A message will confirm that the level has been unlocked.
To unlock this level easily, make your own level with the level editor filled with 5,000 point gaps. 10x multipliers are not valid to get the level. Try making a series of low sloping rails placed this way: \\\\\\\\. Make gaps of 5000 points between each until you run out of gaps. Ride parallel, this way : \\\ <-. Jump up and grind. You should skip on the tops of each one, getting massive points. Eventually you will begin to slow down and grind backwards. If this happens and you do not already have the points, jump
up to other rails until you get the points. If you get the points in a park editor test ride, it will not work. Make sure it is saved and that you do this in a single session.
Burnside level from Tony Hawk's Pro Skater:- Get all thirty covers and two gold medals with all characters.
View rider's ending sequence:- Win any type of medal in both competition levels with any rider to view the corresponding FMV sequence.
Grandma FMV sequence:- Win any type of medal in both competition levels as Grandma.
Neversoft Bails FMV sequence:- Win any type of medal in both competition levels as Tony Hawk.
Best bike:- Win gold medals in both competition levels to unlock your rider's best bike.
Sprocket Stall:- There is only one place where this can be done, and it is the only rail in the level. Go there and grind on it where your bike is completely crooked by the wheels are the opposite way of the rail. You should stall if done correctly.
Dirt track:- Go to the half pipe where it goes to the small place right next to it. Go over that long pipe (over the whole track)
and grind it. The garage door will open, revealing a dirt track on the other side.
Easy win:- When you are in the level that you have to get medals, do a special trick. Then, end heat and you will get a in the 90s in points and an automatic win, if you do not wreck.
Stretched arms:- Unlock Granny and play a session with her. During the session, do an X-Up. Granny's arms will reach out far in
front of her.
La Habra: Extra points:- Turn around from your starting position and go into the first green half-pipe. To the right of the pipe will be the fence that the "R" is on. If you go to the part of the pipe nearest the fence you can trick on to it. Grind trick out to come out with about a fifth of the score. This also includes two gaps, but may not appear every time. Add specials into the mix to get up to 100,000 points.