According to research published in the journal Cognitive Science, toddlers can figure out when their parents are joking, with the help of clear social cues.

For example, if a parent holds up a cup of water to their elbow (as though they’re offering their joint a drink), exclaiming “That’s not how you drink!” helps their child understand that they’re joking. (Without that hint, kids might be left wondering if their elbows are, in fact, thirsty.)

[The science of humor is no laughing matter.] 

The study also found that kids can differentiate between joking and pretending—two activities that, though similar, may contribute to a child’s development in somewhat different ways. Elena Hoicka, a developmental psychologist and one of the paper’s authors, describes the potential benefits that sharing a beverage with your elbow, throwing a rubber chicken on your head, and galloping a block as if on a horse can have for kids.