A Bailer Lars, is a person who always bails out, e.g. you agreed to meet some where or you planed to do something together. If a person is to be named “Bailer Lars”, it's important that he always bail out in the last minute.
40-year old virgin: “Dude, this chick just asked if we wanted to Eiffel Tower her! Damn she's so hot, but she would only do it if we were both up for it. What do you say?”
50-year old virgin: "I don't know... Well all right"
Later at the chick’s place
50-year old virgin: "Mate, I think I'm goanna get myself some cheeseburgers and a strawberry-shake at McD’s, instead”
The chick and 40-year old virgin together: "WHAT????"
40-year old virgin: "Dude, you are such a Bailer Lars"
Kamikaze pilot: "Charlie, Bravo, Alfa, I’m at the location, awaiting orders"
Control Centre: "Broken Arrow, Broken Arrow, you are good to go. This will win the war for us"
Kamikaze pilot: "Mad dog 55 here; Well I changed my mind, I might head in the direction of the vegemite headquarter. I got the munchies, I’ll do the kamikaze thing another day"
Control Centre: "WHAT the F***!!!!! You’re such a Bailer Lars"