The Onion has some great posts on Federer, but generally he's not the source of a lot of laughs, except perhaps when he says something silly in an interview or post match speech. I don't think his crying is funny but maybe some people disagree.
Anyway, I came across this on his Wikipedia page.
Like all Swiss males, Federer is subject to compulsory military service in the Swiss Armed Forces. Unfortunately, long-standing back trouble led him to be declared inapt in 2003 and he was unable to fulfill his obligations. Nevertheless, he did not let it affect his tennis and bounced back to win Wimbledon that year.
It had never occurred to me that his tennis career could have been disrupted because of military service. I love the "unfortunately". It's pretty impressive that despite being physically handicapped he was able to be one of the world's greatest athletes. Imagine how good he could have been if he was healthy!