Q. Why can’t Smurfs swim?
A. Because: #river .forest-dwelling-creatures { color: #12d; float: none; }

An English man, Irish man and Scottish man walk into a bar, but non-one knows they are there because: #bar .man[lang=en], #bar .man[lang=gaelic], #bar .man[lang=celtic] { visibility: hidden; }

Q. Why did the background-image of a chicken cross the screen?
A. Because: #chicken { background: url(/images/chicky-wicky-woo.gif) no-repeat; float: right; }

Your mother’s so fat that .your-mother { display: block; font-weight: bold; width: 100%; border: 200px solid #e77; background: #320 url(/fridge/loads-of-pies.pig) repeat; }

#knock .knock
Who’s there?
An element with an class of ‘knock’ contained within another element with the id of ‘knock’

Q. What do you call an xhtml document with a spade in it’s head?
A. < head >a spade< /head >

Q. Why couldn’t the block element contained in the inline element walk?
A. Because it was invalid

Q. What do you call: a.dear with no < i >’s?
A. A link with the class of ‘dear’ that isn’t in italics

Q. Why was it relatively easy for the vicar to carry a container of holy water?
A. Because: font-weight: normal;

Q. Why was the pillow soft?
A. Because: .pillow { padding: 100px; }

Source: [link]