T-G-I-F vs. S-H-I-T

A business man got on an elevator.

 When he entered, there was a blonde already inside who
 greeted him with a bright,

   "T-G-I-F."

 He smiled at her and replied, "S-H-I-T."

 She looked puzzled and repeated, "T-G-I-F," more
 slowly.

 He again answered, "S-H-I-T."

 The blonde was trying to keep it friendly, so she smiled
 her biggest smile, and said as sweetly as possibly,
 "T-G-I-F."

 The man smiled back to her and once again,
 "S-H-I-T."

 The exasperated blonde finally decided to explain.

 'T-G-I-F' means 'Thank Goodness It's
  Friday.' Get it, duuhhh?"

  The man answered, "'S-H-I-T' means 'Sorry,
  Honey, It's Thursday -- duuhhh