A zeugma is a figure of speech in which a single adjective or verb is used to modify two or more nouns, though the adjective or verb is usually used appropriately or logically with only one of the nouns.  The use of the verb or adjective to modify the nouns can express either literal or figurative meanings.
Because zeugmas are uncommonly used in writing, they are effective at catching the reader’s attention.

Exempli Gratia

Example A :

In the phrase “to wage war and peace,” the word “wage” logically modifies the word “war.”  On the other hand, the word “wage” generally does not apply to “peace,” therefore the verb is appropriately applied to just one of the nouns.

Example B :

“Miss Bolo went home in a flood of tears and a sedan chair.”  – The Pickwick Papers by Charles Dickens

In this example, Miss Bolo literally goes home in a sedan chair.  She only figuratively goes home “in a flood of tears,” which signifies that she left in quite a mournful manner.

The application of one verb to two different nouns resulting in two contrasting meanings makes this sentence a zeugma.

Sources

http://www.wordsmyth.net/live/home.php?script=search&matchent=zeugma&matchtype=exact
http://grammar.about.com/od/tz/g/zeugmaterm.htm
http://www.linguist.org.cn/doc/uc200611/uc20061105.pdf
http://web.cn.edu/kwheeler/lit_terms_Z.html
http://dictionary.reference.com/browse/syllepsis