I think a few people here have talked about the spike in the past and I think it is generally thought of as complete crap.
Stuck with out a cutter I have:
Tried biting the cap off (Never again)
Kind of peeled it off (Works pretty good)
Used scissors (I was a noob and no, it doesnt work)
Used an X-acto knife (Felt like I was operating, it worked out perfectly)
Kitchen knife (Apparently it was a shitty one)
Next time I forget my cutter I will....... Its not gonna happen again lol. After forgetting it a bunch of times I decided to pick up a couple more (one for the car, camera bag, etc.)