It's a delicate dance. You have to be consistantly one of the slowest riders without ever having a bad (even worse than usual) day and getting timed out on a stage. The reward is interviews and fame in Paris and one of the most lucative payouts for post Tour criterium appearances.
With stage 8 in the bag and coming into the first rest day, last year's Lanterne Rouge*, 35 year old Belgian Wim Vansevenant, has moved into the lead for the "red jersey". (Of course, the last place rider doesn't really get to wear a special red jersey - that's just a popular Tour myth.) In a stunning second (to last!) place in the Lanterne Rouge competition is American Dave Zabriskie, holder of the record for fastest Tour TT ever! Multiple stage winner Thor Hushovd is easily in grasp of the Lanterne himself, just five and a half minutes off (ahead of) the pace.
With two big time trials to come, it really doesn't look favorable for Zabriskie's hopes (fears). I'd have to say that the experienced Vansevenant (who cemented last year's honor by getting dropped from the peloton racing up and down the Champs Elysées) is looking good (bad) to repete.
*"Red lantern", like the one hung on the back of the last car of a train.
"The Lanterne Rouge is not a position you go for. It comes for you." Wim Vansevenant, 2006