To compete with s.o. to see who can endure s.t. the longest without stopping; to defeat s.o. by enduring longer than s.o. else in any kind of work.
The -un imp. focuses on the people who are being challenged by s.o.
Lay ya tabōt me' ku nappa.
He was defeated by me in pounding rice (because I lasted longer than he did).
Those people are competing to see who can endure the longest at cutting down weeds because they haven't even stopped and it's already two o'clock in the afternoon.