A “subway acrobat” is someone who performs gymnastic moves on the subway, often using the subway’s poles (or straps). The show is done for free, but the performer usually asks for money after the performance.
 
The term “subway acrobat” has been cited in print since at least 1942. The New York Police Department cracked down on subway acrobats in July 2014.
 
 
Google News Archive
29 August 1942, Spokane (WA) Daily Chronicle, pg. 10, col. 1:
SUBWAY ACROBAT
ALMOST SCALPED
NEW YORK, Aug. 29. (AP)—Matthew Mallahan, 20, was partly scalped on a subway train last night—and there wasn’t a Redskin in sight.
 
Feeling energetic, Mallahan grasped two hand straps and went into a chinning routine.
 
He had failed to consider the whirring electric fan above.
 
8 January 1981, Richmond (VA) Times-Dispatch, “Stories Show Mastery of Form” (Fifty Stories” by Kitty Boyle), pg. G-5, col. 5:
“The Ballet of Central Park” is about a 14-year-old ballerina named Hilary who falls in with a group of Central Park shoeshine boys and subway acrobats, including a young Spaniard named for the poet Federico Garcia Lorca.
 
Google Books
Art and the Subway:
New York Underground
By Tracy Fitzpatrick
New Brunswick, NJ: Rutgers University Press
2009
Pg. 97:
Lawrence returned to the subway as a subject matter in paintings such as Subway of 1938, Subway Acrobats of 1959, and a glass mosaic mural entitled New York Transit for the Times Square station, ...
(Subway Acrobats of 1959 can be seen here.—ed.)
   
New York (NY) magazine—Daily Intelligencer
May 27, 2009 3:01 p.m.
Man Mugged by Subway ‘Acrobats’
By Jessica Pressler
This is unfortunate: A 22-year-old was mugged on the J train by a subway “dance troupe,” the Brooklyn Paper reports today.
 
The violent attack began when the victim started conversing with the dancers after they finished an acrobatic performance near the Lorimer Street stop at around 3:40 a.m. That’s when one of the perps asked the victim if he would like to “see something mesmerizing.” The victim said yes, so the perp pulled himself into the air on the train’s metal bars and unleashed a powerful kick to the victim’s chest. Two other dancers then joined in the attack and started punching and kicking the victim in the head and body.
     
YouTube
Subway acrobats flip underground
AFP news agency
Uploaded on Dec 3, 2010
The New York subway, with its crowds, baby carriages and cacophony, is a challenging venue for an acrobatic show, but it’s not stopping a few guerrilla artists. “LJ”, “Mr. Wiggles” and “THEBESTUKNOW’” have been performing their mix of capoeira, yoga, and down-home style to fellow riders for years. Duration: 02:13.
 
Twitter
Ian Murphy
‏@Ianmurphyartist
N.Y.C. Subway Acrobats Flip Underground: The New York City subway, with its crowds, baby carriages and cacop… http://on.wsj.com/gCvd7A
11:38 AM - 5 Dec 2010
 
Gothamist
R.I.P., Subway “Showtime!”: NYPD Cracking Down On Subway Acrobats
Rebecca Fishbein in Arts & Entertainment on Jul 1, 2014 11:47 am
The NYPD is continuing its crackdown on subway acrobats, with “Showtime!”-related arrests at a sixfold increase since this time last year.
 
According to the AP, cops have arrested over 240 subway acrobats this year, as opposed to the under-40 similar arrests last year. And though the NYPD’s notably been cracking down on illegal subway vendors and panhandlers, they’ve been paying special attention to the somersaulting breakdancers, arresting them on charges like reckless endangerment. “Is it a significant crime? Certainly not,” Police Commission William Bratton told reporters, adding, “Does it have the potential both for creating a level of fear as well as a level of risk that you want to deal with?”
   
ABC6 On Your Side (Columbus, OH)
NYC Police to Subway Acrobats: ‘Sit Down!’
Updated: Tuesday, July 1 2014, 07:05 PM EDT
NEW YORK (AP)—The underground acrobats who flip, somersault and pole-dance among New York City subway riders as trains roll are drawing a new audience - police officers.
 
The New York Police Department is cracking down on the subway showmen who use the tight quarters of the nation’s busiest transit system as moving stages for impromptu - and illegal - pass-the-hat performances. More than 240 people have been arrested on misdemeanors related to acrobatics so far this year, compared with fewer than 40 at this time a year ago.
 
Police Commissioner William Bratton acknowledges he is targeting subway acrobats as part of his embrace of the “broken windows” theory of policing - that low-grade lawlessness can cultivate a greater sense of disorder and embolden more dangerous offenders.