In the cases that I have been involved with in which juries are being selected, I have seen this happen a few times.
As a practical matter, most trial lawyers follow the rule that if someone really, really doesn't want to be on your jury, that you don't want him either (regardless of his likely position on the merits as he may lead to a hung jury or mistrial) and will not contest a challenge for cause even if the potential juror is not legally eligible to be struck but obviously is very unhappy with having to serve.
But, judges don't want to start a rush to get out of jury duty and want to discourage this and use a variety of tactics to do so.
One of the most common approaches that judges take is to extensively probe the potential juror about why he intends to vote as he does in the (usually successful) hope of finding a reason that would not apply to every possible case that could come before the court. (The person making the B.S. claim that he'd find the person guilty usually isn't smart enough to see this coming.)
For example, the potential juror might say that he doesn't believe in drug laws, or that he can't be impartial to immigrants since his cousin was murdered by an immigrant.
Once a judge pins down a reason like that, the judge will often announce that the juror is striken from the pool for this particular case but will stay in the jury pool for the next week or so, until a case that does not present such a problem arises and that the prospective juror must appear each day, all day, until he is seated on a jury or rejected for a reason other than this particular cause.
This leaves the smart alec screwed relative to his original goal to get out of jury duty, and discourages others from following suit.
I've seen this done several times, so I think that it must be something that they teach judges in their annual judicial education seminars.