Readers familiar with American or Canadian football should be able to grasp Held's joke here. For the rest of you, the best I can say is that "Hold 'em!" is what football fans sometimes call out when the opposing team is advancing towards the goal line. (http://artcontrarian.blogspot.nl/2014/02/john-held-jr-flapper-art-and-more.html) Used for a Life Magazine cover.