Thank Goodness Its Friday

A business man got on an elevator in a building.
When he entered the elevator, there was a blonde already inside and she greeted him by saying, “T-G-I-F” (letters only).
He smiled at her and replied, “S-H-I-T” (letters only).”
She looked at him, puzzled, and said, “T-G-I-F” again.
He acknowledged her remark again by answering, “S-H-I-T.”
The blonde was trying to be friendly, so she smiled her biggest smile and said as sweetly as possibly, “T-G-I-F” another time.
The man smiled back to her and once again replied with a quizzical expression, “S-H-I-T.”
The blonde finally decided to explain things, and this time she said, “T-G-I-F, Thank Goodness It’s Friday, get it?”
The man answered, “Sorry, Honey, It’s Thursday.”