Major Margaret Houlihan, head nurse of the 4077 MASH, played to perfection by the late Loretta Swit, was called by the nickname Hot Lips throughout much of the show’s run. But, when was she given this nickname? In the film adaptation of the original book, we witness the moment it happens. But, the show is only loosely based on the book and, given the events of the show, it’s unlikely that the same incident was supposed to have occurred. Yet, Hawkeye calls Margaret Hot Lips in the pilot episode. Just after Hawkeye calls her this name, which predictably upsets her, General Hammond arrives and also calls her Hot Lips. So what gives?

How Margaret Became Hot Lips in the Movie
In the film version of MASH, the public P.A microphone had been stashed under her cot so that Hawkeye, Duke, Trapper, and Radar can listen in on her. She has a passionate rendezvous with Frank Burns and is heard to say, “Ohh, Frank, my lips are hot! Kiss my hot lips!” Trapper then decides to broadcast their date to the rest of the camp, but this plan is interrupted when Margaret hears their voices feeding back on the camp loudspeaker and rushes Frank from the tent.
In the film, this is pretty much the end of Frank Burns as the next day Hawkeye taunts him about their little affair and Burns, played by Robert Duvall, jumps over the table and attacks him. As a result, he is sent away for psychiatric evaluation and is taken away by MP’s wearing a straightjacket. This is the last he is seen in the film. Admittedly, a lot more happened to cause Frank to attack Hawkeye, including Trapper being made chief surgeon over him. Anyway, this is how Hot Lips is given her nickname in the film.
When Was Margaret Given the Nickname Hot Lips In MASH Show?
In the show, we are never informed as to how Margaret got her nickname. During the pilot, Hawkeye calls her Hot Lips. It would seem as if this is already a nickname for her. Then, minutes later, General Hammond arrives and Margaret, as if often the case, is on a first name basis with the general. Upon seeing her he embraces her and calls her Hot Lips. Hawkeye and Trapper exchange shocked glances and repeat “Hot Lips” to each other, seeming surprised that this is her actual nickname. So, in the end, we are left with no clear idea as to why she got the name and why Hawkeye called her that in the first place, only to be surprised when General Hammond used the name.
It may be that Hawkeye and the others had given her the name in the same way as occurred in the film, and were then expressing surprise when General Hammond also knew and used the name. But this is not what seemed to be happening in the show. General Hammond was embracing Margaret, whom he had obviously had more than a casual friendship with, and seemed to be using it as a pet name and something that she was not surprised by, as she would have been had he independently used this nickname that so offended her.
The most likely answer as to how she got the nickname in the show is that it was never written. In other words, the nickname was just taken from the book and the movie and no explanation was contrived as to how she got it.
In the television show, Frank Burns also suffers a mental breakdown brought on by Margarets marriage to Donald Penobscott, but this doesn’t happen until the beginning of the 6th season, while the last we see of Frank is the final episode of the 5th season.
The Name Hot Lips Did Not Last
The character of Margaret evolved greatly through the show and much of this development occurred due to the influence and leadership of Loretta Swit herself. The name Hot Lips did not stick and stopped appearing in scripts. After, she was just Margaret or Major Houlihan. Alan Alda, speaking about Loretta Swit’s passing, spoke about how delighted she was when the name Margaret appeared in the script instead of Hot Lips. According to him, this happened because of what she brought to the character.