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nature calls

phr. (context euphemistic English) Used to indicate that someone (usually the speaker) feels a need to urinate or defecate.

Wikipedia
Nature Calls

Nature Calls is an 2012 American comedy film, released on November 9, 2012 and the DVD version on January 22, 2013. It stars Patton Oswalt, Johnny Knoxville. Rob Riggle, and Patrice O'Neal and features Maura Tierney.

The film is the final on-screen performance of Patrice O'Neal, who died in 2011 from complications of a massive stroke.