I've been seeing literally dozens of threads about these two, and decided to make an official help thread (hopefully stickied soon) to end it all. Thrasher Backboard help credit goes to ipwnskatedemo.
Since the forum is damn near flooded with threads about this, here is a few tips on how to do them.
Thrasher Jake Brown Sesh at Slappy's:
1. Pick up some speed by doing ollies and pumping around the areas, avoiding Jake.
2. When you are happy with the height [I did it at just above the top rail height], pump up the QP by the rail, this is the important part, press RB [R1 on PS3, I think, correct me if I'm wrong].
3. AS SOON as your board is about a foot over the coping, then tweak with the R stick.
You can tweak before you are into the plant too.
Don't stress over it too much, even with that, you're looking towards about 8 attempts minimum.
Thrasher Handplant The Backboard at the basketball court.
1. Set up the two ramps side by side, just in case you fall on the landing. Trust me, I did it with one ramp, and I bailed 4 times in the process.
2. Set up a marker at the tunnel, it should say RETURN TO CHALLENGE AREA where you're at.
3. Go as fast as you can at the QP's.
4. Pump up the ramp, and as soon as you're over the coping, press the RB/R1 button.
5. Land, roll away buttery smooth, and make a taunt at the cameraman, showing him that he is you're *****, not the other way around. Later, you can hit up the bar and say that you figured it out on your own.
If you miss the landing, try configuring the location of the ramps. It can take a while, but I got the PO in the first few configs.
As with the first challenge, don't stress out too much. I didn't have as much trouble with this one as I did with the other one.
Ok, everyone is saying how hard it is to do the Girl challenge. I got it first try, and this is how.
1. Keep matching their tricks until it's your turn.
2. When it's your turn, do NOLLIE TRIPLE HEELFLIP variations. Nollie trip heel, NTH 180, and NTH 360. Don't try to do other triple flips, because the nollie heels flip the fastest and it's the only one that'll make it.
3. When all 3 of them are in the "already been done" list, just do random tricks until you can do the heels again, and just wait it out until you win.
Alternatively, you can also do the challenge this way:
BY: BIGBEN4X4
Ok, for all of us who are stuck on this nightmare challenge I have a solution, and it dose NOT involve 540's or triple flips.
When you start the challenge you'll notice that all of the movable objects nearby vanish, but surely not every object in San Vanelona.
Quit the challenge and venture up the giant spillway. Near the huge drainage pipe you'll see a steel bike rack just like the one you have to jump over in the challenge. Grab that sucker and drag it all the way back to the challenge area.
If you've moved the pic-nic table make sure you reset it. Drag the rack and put it up against and in front of the table.
Start the Challenge
Though the rack may not appear for Eric Kostons first attempt, it will for Mike Carrols. From here on you'll be able to clear the rack like it's not even there but Eric and Mike will simply "Trick Out Of Bounds" allowing you to get past this challenge once and for all.
Here's The Video:
http://skatereel.ea.com/members/2/186499022/20244.aspx
Edit by ChvyVele: as found in this thread:
http://forum.ea.com/eaforum/posts/list/49352.page