Why are some epistemically suspect beliefs so popular? People high in communion, either because they want to make others happy, or because they want to display their niceness, might be particularly keen to share ‘happy thoughts,’ beliefs that might make others happy, even if they are epistemically suspect—for instance, that naturopathy works, or that heaven exists. Across six experiments (N = 1596) we found that: (i) people who self-describe as being high on communion (i.e., nice, kind) are more likely to believe and share happier epistemically suspect beliefs, by contrast with people who self-describes as being high on agency (i.e., competent, dominant); (ii) people prefer to share happier beliefs when wishing to appear nice and kind rather than competent and dominant; (iii) sharing happier beliefs does lead to being perceived as nicer and kinder; and (iv) sharing happier beliefs leads to being perceived as less dominant. We also found a consistent positive bias independent of participants’ personality, with happier beliefs being more likely to be shared and believed. Overall, these results suggest that some happy epistemically suspect beliefs could become culturally successful because they allow their sender to signal niceness and kindness.