I had very brief BBFS with a MILF from 102 Liverpool before. Seems she does it regularly because of how nonchalantly she put my cock in. I just pulled it off so she could resume BBBJ but she took that as a sign to start riding me.
Lucky nothing bad happened, but I pulled out within a few seconds and asked her to finish me in BBBJ. She did clean my cock before doing that, so I'm sure she's taking care not to catch anything, but it's still a gamble.