B737-300 CREW DID NOT SET THE FLAPS TO THE TKOF POS AND HAD A TKOF WARNING HORN SOUND.

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IMPROPER FLAP CONFIGN FOR TKOF. AFTER PUSHBACK; I CALLED FOR 'FLAPS 5 AND PRETKOF CHKLIST.' BEFORE THE FO COULD RESPOND; LAS RAMP ASKED US IF WE COULD ACCEPT A RWY 19 TKOF. THE FO RESPONDED 'STANDBY;' AS HE RECALCULATED TKOF DATA FROM RWY 25R TO RWY 19L AND REPROGRAMMED THE FMC. ONCE COMPLETE; I CALLED FOR THE PRETKOF CHKLIST AGAIN; AND WE WERE INTERRUPTED A SECOND TIME BY LAS RAMP INQUIRING ABOUT RWY 19. AFTER RESPONDING AFFIRMATIVELY; WE PICKED UP THE PRETKOF CHKLIST WHERE WE THOUGHT WE LEFT OFF (BUT WE MUST HAVE MISSED THE FLAPS POS CHALLENGE AND RESPONSE). WE FINISHED OFF THE CHKLIST THEN CALLED FOR TAXI. WE TAXIED OUT TO RWY 19L AND WERE INSTRUCTED TO TAKE THE RWY. AS WE TOOK THE RWY; I CYCLED THE THROTTLES FOR A CONFIGN WARNING 'HORN CHK;' AS IS MY HABIT. I WAS SURPRISED TO HEAR THE TKOF WARNING HORN SOUND. WE THEN NOTICED THE FLAP INDICATOR WAS AT 'ZERO.' AFTER A BRIEF EXCHANGE WITH THE FO; WE SELECTED FLAPS 5 AS TWR CLRED US FOR TKOF. WE ACCEPTED THE CLRNC; BUT DELAYED TKOF THRUST WHILE THE FLAPS WERE IN MOTION; AND WE DOUBLECHKED THE COCKPIT FOR ANY OTHER OVERSIGHTS. AFTER WHAT SEEMED AN ETERNITY; I ADVANCED THE THROTTLES; BUT WAS A BIT PREMATURE; AS THE FLAP INDICATOR HAD NOT FULLY REACHED POS 5. THE TKOF WARNING HORN SOUNDED AGAIN FOR A FEW BEEPS BEFORE SILENCING ITSELF; AS THE INDICATOR FINALLY REACHED POS 5. THE FO AND I BOTH VERIFIED AND AGREED THE ACFT WAS IN A SAFE TKOF CONFIGN; AND WE CONTINUED THE TKOF ROLL. THE TKOF CONTINUED NORMALLY WITHOUT FURTHER INCIDENT. UPON REFLECTION; I FELT I MADE A POOR DECISION IN SELECTING TO CONTINUE THE TKOF GIVEN THE UNUSUAL CIRCUMSTANCES. I SHOULD HAVE PERFORMED A SLOW SPD ABORT AND TAXIED OFF TO RUN THE ENTIRE CHKLIST ONE MORE TIME. DESPITE OUR PERCEPTION THAT WE HAD CORRECTED THE PROB; WE WERE CONFIDENT OF A SAFE TKOF CONFIGN AND WERE AT A SLOW SPD ROLL. THE FACT THAT WE HAD TO RECONFIGURE THE ACFT ON THE RWY SHOULD HAVE PROMPTED A SLOW SPD ABORT. ADDITIONALLY; IT IS CLR THAT EVEN MINOR INTERRUPTIONS CAN BE ENOUGH OF A DISTR TO CAUSE AN ITEM TO BE MISSED ON A CHKLIST. I; FOR ONE; WILL ALWAYS RESTART THE ENTIRE CHKLIST IN THE FUTURE. WE DID NOT CONSIDER THIS AN ABORT AND; THEREFORE; DID NOT FILE AN IRREGULARITY RPT. AS THERE WAS NO ACFT MALFUNCTION; NO INFO ENTRY WAS MADE IN THE LOGBOOK. I REALIZE THAT COMPANY HAS TAKEN GREAT PAINS TO AVOID THIS VERY TYPE OF INCIDENT THROUGH FOCUS ON THE NEW CHKLIST PROCS. ASAP PROGRAM AND EMPHASIS ON CONSERVATIVE DECISION MAKING. I AM GREATLY EMBARRASSED THAT I MISSED THE SINGLE HOTTEST ITEM OF FOCUS; AND I AM SURE THAT THE HUMILIATION OF TAXIING OFF THE RWY AND BRINGING SHAME UPON MYSELF AND COMPANY IN FRONT OF A HALF DOZEN OTHER CARRIERS PROBABLY CONTRIBUTED TO ME ATTEMPTING TO MITIGATE MY MISTAKE. I ALLOWED MYSELF TO FEEL RUSHED AND WAS OBVIOUSLY FLUSTERED AS EVIDENCED BY MY SLOPPY TKOF PROCS. ALTHOUGH THIS HAS BEEN TOUGH ON THE EGO; THIS INCIDENT HAS TAUGHT ME A VALUABLE LESSON; AND I RESOLVE TO NOT ALLOW THE PERCEPTION OF FEELING RUSHED OR THE FEAR OF LOOKING BAD AFFECT MY DECISIONS IN THE FUTURE. SUPPLEMENTAL INFO FROM ACN 571925: WE DON'T SET FLAPS PRIOR TO TAXI. THIS OCCURRED AFTER THE 'AFTER START CHKLIST' WAS COMPLETE. WHILE I WAS CHKING THE FLAPS; THE CAPT PUSHED THE THRUST LEVERS UP; AND WE GOT THE BEEPS; WHICH THEN STOPPED AT THE SAME TIME I CALLED OUT THAT WE'RE OK. WE LET OURSELVES BE PUSHED; AND MADE A BAD DECISION NOT TO ABORT. I LET DISTRS; PERCEPTIONS; AND A 'GO' ATTITUDE INTERFERE WITH MY NORMAL DISCIPLINED APCH TO FLYING.