Hiyo,
Until likely and such get incorporated into the ChucK source, try this...

fun int likely() {
    return (maybe || maybe);   
}

fun int unlikely() {
    return (maybe && maybe);
}

It won't let you set likely or unlikely to a certain value, but as some have posted, there really is no exact value for these special words. likely() does give you a higher chance of hitting (getting true) and unlikely() has a lower chance of hitting so it does the job for me. If you want to specify how likely or unlikely something is you can also include these functions....

fun int likely(int howLikely) {
    maybe => int answer;

    

    for (0 => int i; i < howLikely; i++)
        answer || maybe => answer;

    

    return answer;
}

fun int unlikely(int howUnlikely) {
    maybe => int answer;

    

    for (0 => int i; i < howUnlikely; i++)
        answer && maybe => answer;

    

    return answer;
}

The argument passed makes the function more or less likely to return true (e.g. setting howLikely to 3 results in 93% hits, while setting howUnlikely to 3 results in 6% hits). Again, results will deviate a little over time, but I think that's desired if you're throwing words likely likely, maybe, and unlikely into your ChucK programs.

I'm attaching a file that includes these methods and tests that run these methods several times, printing out the number of hits. Sorry about the copy-and-paste abuse. Below is a transcript of the log the program prints for 100,000 trials using different variations of the above methods.

Best,
mark