PLT OF C152 ON NIGHT FLT ENTERS CLASS B AIRSPACE WITHOUT CLRNC.

Narrative

I DEPARTED AT NIGHT WITH ANOTHER PLT IN A C152 TO SHOW HIM SOME OF THE LCL RTES AND AIRSPACE. MY ORIGINAL INTENT WAS TO FLY UP THE VFR CORRIDOR BTWN DCA AND IAD AT 1400 FT MSL WHICH WOULD KEEP ME CLR OF BOTH CLASS B AIRSPACE STRUCTURES AT DCA AND IAD. WHILE NAVING VIA VARIOUS GROUPS OF CITY LIGHTS AND HWYS IN THE METRO AREA THAT I THOUGHT WOULD GUARANTEE OUR BEING IN THE VFR CORRIDOR; I WAS MOST SURPRISED WHEN THE OTHER PLT ASKED WHAT ARPT WE WERE PASSING. I THEN NOTICED RWY 1L/19R AT IAD OFF THE R WING. WE ESTIMATED OUR DISTANCE FROM IAD AT ABOUT 3-4 MI; WELL WITHIN THE 7 MI RING AROUND IAD THAT IS RESTR FROM GND LEVEL WITHOUT BEING IN CONTACT WITH ATC. AT THE TIME I WAS NOT TALKING WITH ANY ATC FACILITY; BUT I AM QUITE SURE THE INCIDENT WAS NOTICED BY APCH CTL AND THE TWR CTLR AT IAD. WE IMMEDIATELY EXITED THE CLASS B AIRSPACE AS QUICKLY AS POSSIBLE WITH (SEEMINGLY) NO FURTHER CONSEQUENCES OTHER THAN RUFFLED PRIDE; IRRITATION AT MY LACK OF SITUATIONAL AWARENESS AND DISGUST OVER ANY PROB I MAY HAVE CAUSED FOR THE ATC FACILITY AT IAD. I KNOW THE INCIDENT RESULTED FROM MY OVERLY COMPLACENT ATTITUDE OF BEING (SUPPOSEDLY) COMPLETELY CONVERSANT WITH THE AIRSPACE LIMITATIONS AROUND THE WASHINGTON; DC; AREA. I SHOULD HAVE CONFIRMED MY POS WITH THE NAVAIDS AT MY DISPOSAL (MAINLY VOR RADIALS) TO ESTABLISH MY POS BEYOND ANY DOUBT. COMPLICATING THE MATTER WAS MY INVOLVEMENT IN SHOWING THE OTHER PLT THE AREA AT NIGHT TO TRY TO HELP HIM GET ORIENTED. A RAPIDLY PRECESSING DIRECTIONAL GYRO THAT WAS ABOUT 40 DEGS OFF THE PROPER COMPASS HDG WHEN I REALIZED WE WERE IN IAD'S AIRSPACE ADDED TO THE PROB. THIS INCIDENT HAS HUMBLED ME TO NOT TAKE ANYTHING REGARDING ACFT OP FOR GRANTED NOR TO BECOME COMPLACENT ABOUT MY OWN PLTING ABILITIES. FLY THE AIRPLANE FIRST -- THEN TAKE CARE OF ANYTHING ELSE THAT MIGHT SEEM TO BE OF IMPORTANCE.