A CodePen by Francisco Campos.

index.html

<ul class="tt-wrapper">
  <li><a class="tt-gplus" href="#"><span>Google Plus</span></a></li>
    <li><a class="tt-twitter" href="#"><span>Twitter</span></a></li>
      <li><a class="tt-dribble" href="#"><span>Dribble</span></a></li>
        <li><a class="tt-facebook" href="#"><span>Facebook</span></a></li>
          <li><a class="tt-linkedin" href="#"><span>LinkedIn</span></a></li>
            </ul>

style.css

.tt-wrapper li a {
 display: block;
  width: 68px;
  height: 70px;
  margin: 0 2px;
  margin-top: 50px;
  outline: none;
  background: transparent url(http://tympanus.net/TipsTricks/CSS3Tooltips/images/growcase_the_social_gunman_icons.png) no-repeat top left;
  position: relative;
  float: left;
}

.tt-wrapper li .tt-gplus {
  background-position: 0px 0px;
}

.tt-wrapper li .tt-twitter {
  background-position: -68px 0px;
}

.tt-wrapper li .tt-dribble {
  background-position: -136px 0px;
}

.tt-wrapper li .tt-facebook {
  background-position: -204px 0px;
}

.tt-wrapper li .tt-linkedin {
  background-position: -272px 0px;
}

.tt-wrapper li a span {
  width: 100px;
  height: auto;
  line-height: 20px;
  padding: 10px;
  left: 50%;
  margin-left:64px;
  font-family: "Alegreya SC", Georgia, serif;
  font-weight: 400;
  font-style: italic;
  font-size: 14px;
  color: #719DAB;
  text-shadow: 1px 1px 1px rgba(0,0,0,0.1);
  text-align: center;
  border: 4px solid #FFF;
  background: rgba(255,255,255,0.3);
  text-indent: 0px;
  border-radius: 5px;
  position: absolute;
  pointer-events: none;
  bottom: 100px;
  opacity: 0;
  box-shadow: 1px 1px 2px rgba(0,0,0,0.1);
  transition: all 0.3s ease-in-out;
}

.tt-wrapper li a span:before,
.tt-wrapper li a span:after {
 content: "";
position: absolute;
bottom: 15px;
  left: 50%;
margin-left: -9px;
width: 0;
  height: 0;
  border-left: 10px solid transparent;
  border-right: 10px solid transparent;
  border-top: 10px solid rgba(0,0,0,0.1);
}

.tt-wrapper li a span:after {
  bottom: -14px;
  margin-left: -10px;
  border-top: 10px solid #FFF;
}

.tt-wrapper li a:hover span {
  opacity: 0.9;
  bottom: 70px;
}

CSS needs refining, the a:hover tooltip is off in terms of positioning.