In this article, we explore the collective identity of feminist activists as expressed on Twitter in the context of "Day Without A Woman." We conceptualize collective feminist identity by drawing upon literature on identity, feminism, and social movements. We expected to find a politically-defined group boundary around supporters of "Day Without A Woman." Using the online tool Netlytic, we collected tweets posted from accounts in Washington D.C., New York City, and Los Angeles. In a preliminary step, we performed a word count analysis and coded frequent words within the collected tweets into categories of meaning. Based on these categories, we drew a sub-sample of tweets, which we scrutinized in-depth using discourse analysis. Through this qualitative analysis, we show that the group boundary of the supporters of "Day Without A Woman" is defined by the common denominator of their negative relation to Donald TRUMP. While the supporters stress the relevance of feminist claims, barriers to identifying as a feminist seem to persist, as reflected in those whom we call "flexi-feminists." The boundary between supporters and non-supporters of "Day Without A Woman" hence seems to broaden from a line to a space which can be occupied without complete group entry. In this space and beyond, supporters express feminist identity through an "us" versus "him" logic.