This article explores the effects of heteronormative assumptions on the interpretation of interaction. It considers two pieces of data that, based on the kinds of alignments shown, might be seen as flirting. However, through both perception experiments and discourse analysis, It is shown that these are rarely considered to be flirting if they take place for ‘same-gender’ interactions. These results demonstrate the power and effect of ‘background knowledge’ about sexualities on the interpretation of talk.