You may think that se taper means “to hit oneself”. Theoretically, it can have this meaning, but very often it is an expression that can mean several things. The most common meaning is “to undergo”, “to do something difficult or unpleasant”, “to do a chore”.
L’ascenseur est en panne, je suis obligé de me taper les quatre étages à pied.
The elevator is out of order, I have to walk all four flights of stair by foot.
J’ai un livre à lire pour demain, faut encore que je me tape cent cinquante pages.
I have a book to read until tomorrow, I still have 150 pages to endure.
C’est à ton tour de te taper la lessive !
It’s your turn to do the laundry!
It can also mean “to have sex with someone”.
T’es au courant que Pierre s’est tapé Julie ?
Do you know that Pierre did Julie?
The similar-sounding expression s’en taper (note the en) is one of the many ways to say you don’t care about something.
Arrête de me saouler, je m’en tape de ta vie !
Stop annoying me, I don’t give a damn about your life!
Listen to the examples: