I've been able to implement something like this to great effect. Every time I notice that I've been behaving in a very silly way, I smile broadly, laugh out loud and say "Ha ha! Gotcha!" or something to that effect. I only allow myself to do this in cases where I've actually gained new information: Noticed a new flaw, noticed an old flaw come up in a new situation, realized that an old behavior is in fact undesirable, etc. This positively reinforces noticing my flaws without doing so to the undesirable behavior itself.

This is even more effective when implemented in response to someone else pointing out one of my flaws. It's a little more difficult to carry out because I have to suppress a reflex to retaliate/defend myself that doesn't come up as much when I'm my own critic, but when I succeed it almost completely eliminates the social awkwardness that normally comes with someone critiquing me in public.