Stealing the blanket.

Snoopy and Linus Van Pelt from Charles M Schulz's Peanuts.

Snoopy often tries to take Linus' blanket by running up and trying to grab it out of his hand. This really annoys Linus. Snoopy also does the same thing to Charlie Brown when he holds it in the May 19, 1966 strip, with Charlie Brown saying he has confused him for Linus. In a storyline from November 1971, Linus asks Snoopy to take his blanket and not to give it back no matter how much he begs for it. Snoopy loves watching Linus beg. The beagle then makes the blanket into two sport coats (one for him and one for Woodstock). The next day, Linus realizes he is cured but then Charlie Brown feels bad about what happened, and buys Linus a new blanket. Linus screams and says "Now I'm hooked again!" to which Charlie Brown just replies, "I thought I was doing the right thing."

As noted out above, only once has Linus actually returned the blanket to him after noticing that Linus was digging up the whole neighborhood (and his doghouse) to find it, so Snoopy took the chance to dig it up himself and return it, to which he replies that every now and then his existence is justified.