.slideToggle() is being triggered many times?

.slideToggle() is being triggered many times?

I'm trying to create a Tumblr theme in which the links and post
information slide in when you click a + sign. (My test blog is at
http://noitsnotitsnotokay.tumblr.com/)
I'm quite the begginner at JavaScript, but I was able to work it out for a
links menu with the following code:
<span class="btn">+</span>
<ul class="lks">
<!-- various links are here -->
</ul>
<script>
$("ul.lks").hide();
$("span.btn").click(function () {
$("ul.lks").slideToggle("slow");
});
</script>
But I also have a piece of code that applies to all posts, for the post
information. I used nearly the same code, but, as you can probably see, it
slides in and out various times.
<div class="pstinfo">
<!-- info is here -->
</div>
<span class="plsign">+</span>
<script>
$("div.pstinfo").hide();
$("span.plsign").click(function () {
$("div.pstinfo").slideToggle("slow");
});
</script>
It seems that the button's order and the way I name the classes in the
JavaScript isn't changing much...any tips?