Here is one of the XP2006 workshop antipatterns the group worked on.

Poor Solution:
Concurrent work on to many stories
None of the stories are done at the end of the iteration.
All stories are in progress.

Forces:
Desire to go as fast as possible
Big stories are not split (seem to be unsplitable)
Belief that multitasking is faster

Consequences:
Stories don’t get finished
No data to plan the next iteration
The team feels bad
The team gets blamed
There is nothing to integrate

Better solution:
Split stories so they can be completed
Take on fewer stories per iteration
Minimize work in progress

Exceptions:
None