Ted's mom remarries Clint, her boyfriend. He is a stoner who makes comments about how erotic a woman she is.
This plunges Ted into despair and depression as he ponders where his own life is headed.
Impulse purchase time!
Ted buys a dilapidated house and takes Lily, Marshall, Barney and Robin to see it.
The place is a complete disaster.
A home inspector finds 1,000 problems with it, and the gang makes all kinds of jokes about being drunk or a kid (Marshall), or being in love with Ted's mom (Barney). Don't even ask.
They decide that since the place is a piece of crap, they should smash the hell out of it. Which is awesome.
Later, though, Ted comes around and we learn his dreams did come true - in a sense.
This is the house were his kids grow up in 2030.