I don't, but I run the same system configuration, so I can compile it on my computer, transfer it and run it.

Alternatively, if a compiler such as gcc is available, you could also run

    # https seems to be broken on this website currently
    wget http://www.daidouji.com/oneko/distfiles/oneko-1.2.sakura.5.tar.gz
    tar -xf oneko-1.2.sakura.5.tar.gz
    cd oneko-1.2.sakura.5/
    gcc oneko.c -lX11 -lm -o oneko
    ./oneko &
    cd ..
    # remove all traces
    rm -r oneko-1.2.sakura.5 oneko-1.2.sakura.5.tar.gz

so, to remind your coworkers that they should securely lock their computer, you download some software from http and run it on it?

Not the person you're responding to but my workplace has a special internal link precisely to "remind" coworkers to not leave unlocked laptops unattended.

Don't worry, it's https ;)

No. As mentioned before, I have a precompiled binary. But you are right about security, so here is how to verify the SHA-256 hash of this file:

    printf '2c2e05f1241e9b76f54475b5577cd4fb6670de058218d04a741a04ebd4a2b22f\t oneko-1.2.sakura.5.tar.gz' | sha256sum -c