Ricky Walden, the reigning Shanghai Masters champion, has made a 141 total clearance using '16 reds' at the Maplin UK Championship qualifiers.
He got a free ball at the start of the frame from Mark Davis's foul. Of course the free ball counts as an extra red.
Four years ago, Jamie Burnett made a 148 - the highest break in the history of professional snooker - in this way.
I recall Steve James made a '16-red' clearance at the Crucible against Alex Higgins in 1990. It's happened a number of times but is still relatively rare.