jimjams

Merriam-Webster's Word of the Day for March 27, 2011 is:

jimjams • \JIM-jamz\  • noun plural
: jitters

Examples:
Just thinking about my presentation today gives me the jimjams, confided Joseph to his coworker.

'Now, don't make me repeat myself,' the man said, still musical but jittery, as though talking to kids gave him the jimjams. -- From Ingrid Law's 2008 novel Savvy

Did you know?
When jimjams entered English in the mid-19th century, it probably referred to a specific kind of jitters -- the delirium tremens, a violent delirium caused by excessive drinking. Jimjams is not particularly common today, but when it is used in current American English it means simply jitters. Etymologists aren't sure about the origin of the term. Some speculate that it came about as an alteration of delirium tremens. Others, though uncertain of the origin of jim and jam, notice that the word follows a pattern of similar words in which one sound is repeated or altered slightly. Interestingly, other words for jitters were formed in the same repetitive way -- whim-whams and heebie-jeebies are examples.