I have a regular day job. I was sitting in a business meeting when one of the owners from the other company walked in to join the meeting. ( a frequent visitor). I almost fell out of my chair and my knees were weak when I stood up to shake his hand. I pulled it together and finished the meeting and said nice to meet you,  Look forward to doing business with you. He smiled and said my pleasure. I promptly left with contract signed and an email from him saying he always wondered where I worked. We have been able to maintain both working relationships with discretion. But it rattled me to the point I thought I would throw up. The guys aren't always the ones that have to be discreet.