Hi everyone!
It looks like many programmers need to send UNCHECKED checkboxes.
I found an "elegant" way to do just that!

1. check for checked value true or false:

<input type="checkbox" id="q11" value="" name="too_busy" onClick="yesno(this.id);">

2. if false, set the INPUT VALUE to "no" or whatever...
3. FORCE the check box to BE CHECKED
here is the JavaScript:

function yesno(q) {
qc = document.getElementById(q).checked
qn = document.getElementById(q).name
if(!qc) {document.getElementById(q).checked = 'true'; document.getElementById(q).value = "NO"} else {document.getElementById(q).value = "Yes" }
}

4. SUBMIT it by javascript: document.form.submit();

In PHP $_POST
will have a YES for a checked box
and a NO for an UNCHECKED box.

I hope it helps anyone.
GoodLuck!