To make a sacrifice for the good of others. Originally a military term for when a junior officer would deliberately fall to cover a grenade - the explosion from which would kill a far greater number of his side if he didn't. In particular, it would be when a junior officer would make this sacrifice for a senior one - to protect the commanding officer for the benefit (supposedly) of the army.
Its meaning has been expanded to cover things like taking the blame for a team-fuckup (eg. at work) or humpin a dawg so (as said above) your mates can get into the pretty ones.
1. A lawyer specialising in personal injury claims usually representing people against local authorities or large companies.
2. Derogative description for a personal injury lawyer who specifically seeks out clients for tripping and slipping cases against big companies. Certainly in the US, this is because the lawyer's fee will be a percentage of the client's damages award - therefore making it profitable to find injured former employees of big companies.
1. Q: What sort of practice is it?
A: Oh, he's an ambulance chaser.
2. A: "That guy who got his arm
mangled up in our machine is suing"
B: "Who's he got?"
A: "Some ambulance chaser."