Since your wife has the bus pass, raid the laundry quarters.
Arrive late at proposed meeting place.
Do not try to catch up on life. Jump right in.
Instruct your friend to take off his shoes, put in the earplugs, put on a blindfold, and stand on the throw rug. Call this a Sensory Deprivation Brainstorm.
Prepare audio equipment. Record everything.
Say, "Okay, Go"
Draw sketch notes for 10 mintues as he talks. (Insert sketch notes here)
Then make friend stand on head and say it another way again.
Discover your topic.
Go home, close the door, and write the book.