[T.G]

You could use a razor as previously suggested, or you could use scissors, just don't try and take the whole cap off, just the tip, you're just interested in going through the wrapper, not into the filler. It'll be more of an oblong cut than what a guillotine leaves.

You could also:
- pick the cap off with your fingernail.
- bite the cap off.
- poke a hole through the cap with an angular object, like the point of a knife, a skewer, a guitar pick, the back of a wooden match, etc. For the flat objects, once they are inserted, twist a few degrees to open the hole up (ala the "cigar spike").
- and so on...