In software development bugs are a fact of life and so are excuses such as this popular one. Often enough code works on one machine, but not the other, shrugging it of is mostly not an accepted solution though.
A funny design for programmers with a sense of humor. While simplistic, it attracts attention through the witty unicode emoticon for shrugging, an infamous meme used in tech and programming related communities. Wear this shirt at work and it'll handle this excuse for you.