Now, I love me a screwball comedy and a madcap heroine--and to judge by my spouse I also love me a relentless, obstreperous goofball--but within the profession and among my peers I find this particular shtick, and the insecurity and immaturity that underlie it, to be getting old. In the same way that the roles of ingénue and wunderkind have their expiration date, so too does the role of loveable screwup.
Here's a cheat sheet to let you know when you've outgrown the part:
-you have tenure
-you have a book in print
-you've had more than one tenure-track job (assuming more than three years total)
-you advise doctoral students
-you've been an invited or keynote speaker
-you're on chit-chatty terms with senior scholars in your field
-you meet random people at conferences who know your work
If any one of the above--but especially if more than one!--is true, it's time to move on. You can still be zany and fun, playful and self-deprecating, and you can still shut down the conference bar every night. You can also, of course, still be prey to deep fears and anxieties. But you can't act like the new guy or gal, the brash or naive youngster, the one who will never be taken seriously.
It's someone else's turn. You've made it. Give way to the grad students and new PhDs.