Why do Chinese people always say “死(sǐ) die?”

Lily hasn’t seen her friend Tom for several days. She decides to give Tom a phone call.

Conversation:

Lily: Nǐ zài gān shénme? Wǒ zhè jǐ tiān dōu méiyǒu jiàn dào nǐ. Lily: 你 在  干    什么?    我  这  几天  都    没有    见   到  你。 …