Speaking at the Norwood Annual Dinner for Jewish Charities, the Uxbridge MP said: "I got a letter through my door the other day, as usual from myself. This one asked me to enter the consultation about Crossrail 2, and I made enquiries about this, and got TfL to produce the map.
"It doesn't just go through my backyard, it goes absolutely under my house. They said it was 30 metres under, but it's only 20 metres, so I'm getting very apprehensive. In fact, I haven't even dared tell my wife about this wonderful thing I'm doing for our property."
The consultation for Crossrail 2, which will stretch from Broxborne to Shepperton, Chessington and Epsom, began last month. The project is expected to boost the economy by £1.2bn, including thousands of new jobs and new homes.
If it receives the go-ahead from the Treasury, work is expected to begin in the next few years and completion is set for 2030.
In the past Johnson has argued it is essential to ease overcrowding as the population of London and the surrounding areas sky-rockets.