Humor can promote bonding and bring people closer. However, due to lack of common knowledge regarding cultural references, non-native speakers of the common language (NNS) may have difficulties in understanding and appreciating the humor shared among native speakers of that language (NS). Humor that is intended to promote bonding might end up differentiating those who don’t get it from those who do. Especially in NS dominant culture and context, NNS may miss out when NS are perhaps bonding the most around shared humor. This dissertation provides a systematic understanding of the challenges of sharing humor across linguistic and cultural boundaries. Through in-depth interviews, the first study identified the potential misalignment in NS and NNS’s assumptions about one another’s knowledge as an underlying reason that may account for both the sources of confusion and the interactional challenges perceived by East Asian NNS in sharing American NS humor. The second study further verified this by evaluating NS and NNS’s abilities to estimate each other’s knowledge using an online experiment.