The speaker was talking about how difficult a final exam was. Given the context, this is a mash up of “hit me like a ton of bricks” (to surprise or shock someone) and “hit a wall” (coming up against an insurmountable obstacle). The exam must have been difficult and a surprise! The confusion is obvious: both expressions contain the word “hit” and certainly walls can be made of bricks. The expression “hit a wall” is also sometimes stated “hit a brick wall”, making the two expressions have even more commonality. Perhaps the speaker is a Pink Floyd fan as well. A big thanks to Adam Jacob for hearing this one and passing it on.