When someone is looking at a screen, notebook, newspaper etc) over the main user's shoulder or from the side.
It can be with or without consent.
To peek, glance, look slyly
Husband: Shop shoulder browsing me, I am not looking at dirty pics!
Wife: well I have to make sure, dont I?
Jim: Man we should check this bar out. The ambiance looks great in the photos.
Ross: Gimme the laptop, let me see.
Jim: Come over here and see (shoulder browse). I am not handing you my precious laptop!
Rachel: Mommy! she keeps shoulder browsing me and wont let me read my email in private.
Sarah: She is emailing to boys from her phone!
Mom: Sarah leave her alone! Rachel you know I have the password to your email so keep it clean.
"Dude I totally shoulder surfed this test" (cheated by looking at other's tests)
When a person sitting next to you in a bus, airplain etc reads your magazine, newpaper.