in magic if you have no cards in your hand how do you discard a card?

[Seismic]

in magic if you have no cards in your hand how do you discard a card?

[Arix]

You don't.

[Seismic]

then what do you do?

Because my friend played a card asking me to discard and I didnt have any cards so he told me I lose the game, and I told him he cannot target me with that card since I am an illegal target, who is right?

[Arix]

Neither of you. You're a legal target, you just don't do anything, because you can't. That's really all there is to it.

[Twanos]

Your friend may be getting confused with if you have no cards in your library and you are required to draw a card and can't you lose the game.