If you had the option to add new features to your primary language, what would they be? Is there something from a foreign language you'd like to import to your primary language?

A couple examples:

• A prefix to indicate intensity or degree. BBS/early hacker jargon had terms like "k-rad" to mean 1000x (2^10?) as radical as "rad" without the prefix.
  That Montessori preschool was t-cool but why would they think calling it "Hobbledehoy" was a good idea?
• Making an indication of how confident you are in an a statement obligate and easy. I hedge all the time because I think it's important to convey, but it's clunky. We do a bit of that non-verbally but that doesn't translate to text, and has the other complications of non-verbal cues.
  It would be nice if there was an established vocabulary to quickly convey things like "experienced first-hand, repeatedly", "99% certain", "I've heard but never looked into", etc. From there it would be nice if this was as required as the gender, in gendered languages.

For me, it's definitely the topic particles in Japanese. It just seems like a really interesting thing that is a reason enough to want to learn Japanese, even excluding other great features it has. Here some info on them.