[Decode]

<style>
	span {
		display: none;
	}
</style>

<div>
	<button onclick="toggle(this.nextElementSibling)">Toggle</button>
	<span>Вася лох!</span>
</div>

<div>
	<button onclick="toggle(this.nextElementSibling)">Toggle</button>
	<span>Петя лох!</span>
</div>


<script>
	function toggle(elem) {
		elem.style.display = (elem.offsetHeight) ? '' : 'block';
	}
</script>