Typically, these types of larger all-in bets are attempting to exploit an overly wide range from both the pre-flop raiser and the pre-flop re-raiser (with much more weight on the pre-flop re-raiser's tendencies).
The benefit to the over bet in this instance is that it greatly incentivizes a fold from the original pre-flop raiser who only has 3 big blinds invested, while also forcing the pre-flop re-raiser to call or fold. Because the all-in player can no longer fold, he does not need to worry about being re-bluffed by an aggressive opponent.
Typical hands that do this have solid equity when called and are looking to take advantage of folding out a lot of value re-raises against the pre-flop raiser that aren't quite strong enough to call off the remaining 81 big blinds to potentially win the 112 big blind pot (assuming the pre-flop raiser folds).
A good example of a hand that might take this line is something like AJs or 66. Cold four betting (re-re-raising) to a smaller size may be profitable, but like we mentioned, opens the four bettor to being re-bluffed and put into a close decision with these types of marginal hands. If the four bettor (the re-re-raiser) determines that he has enough folding equity to make up for his likely relatively poor equity the times that he is called (likely by a range of JJ+/AK), then the play has merit.
Negatives of the play are that it is difficult or non-sensical to balance in many ways. In other words, you only have so many combinations of AA pre-flop and you usually want to play them in the most valuable way, which is probably going to allow for your opponent to bluff you off of a potentially weaker holding. So you probably don't see many people making this bet with AA or KK, and that means hands like AQs go up in value when facing this type of all-in. It also means that if you want to adapt this strategy that you need to understand if your opponent is capable of calling off bets lightly. The more capable your opponent is, the better off you are going with the more deceptive strategy of four betting to a smaller size (typically around 20-27 big blinds) and allowing your opponent to make a larger mistake of flatting a dominated hand or re-bluffing with a very weak hand like A5s too often against your strong range.
With this type of strategy, you're basically saying "hey, I have a decent hand, what do you have?". So unless your opponent(s) are just going wild pre-flop, it's usually going to best to opt for the more deceptive play. If you see someone doing this regularly against you, then you may want to tighten up your re-raising range for value against particular players and/or call slightly lighter than your pot odds
suggest because you're more likely up against a weaker range than the size of the bet suggests.