A businessman got on an elevator in a building. When he entered the elevator, there was a blonde already inside and she greeted him by reciting the letters, "T-G-I-F."  He smiled at her and replied, "S-H-I-T." 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 possible,"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, "S-H-I-T: Sorry Honey, It's Thursday."