any of the above definitions is good. but the following probably provides an dramatic example of the words in use.
A pipe dream is a girl that you dream about laying pipe to, although it will probably never happen.
"you were supposed to be a side affect of the drugs"
"I'm not a hallucination"
"You are a pipe dream"
all your hopes and dreams as a kid
When I was a kid I wanted to be a pirate and ride a dragon. Alas, it was nothing but a pipe dream.
The belief in God, heaven, jesus, salvation etc
that weirdo over there is chasing pipe dreams that he will go to heaven.
A dream that usually occurs during a short nap that leaves its victim with a large and often untimely errection.
That pipe dream came at the wrong time, now i have to hide my wood for an hour.
A rooster sitting on a doorknob in hopes of hatching a hardware store.
I should remove that doorknob on the chicken coop, and install a simple latch because that young rooster seems to have a cockerel's pipe dream.
An affliction where a person has an inability to finish any task, because of constant fantasies of anal sex with Hispanic women.
"Jenkins you change that tire yet?" "No boss, I was lost in an Arizona Pipe Dream, the one where I paint the head of my Johnson like Yahweh and bend Consuela over a saw horse and deliver the holy spirit."