<script type="text/javascript">
<!--
var flg = false;
function fuck(thatForm) {
if(!flg) {
flg = true;
thatForm.submit();
}
return false;
}
//-->
</script>
<form name="form_name" action="hogehoge.com">
<input type="image" src="hogehoge.jpg" onclick="return fuck(this.form);">
</form>