<div class="bubble">
  
  <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p>
  
</div>

.bubble {
  width: 240px;
  padding: 10px;
  position: relative;
  border-radius: 10px;
  background: red;
  color: white;
}
.bubble:after {
  content: '';
  position: absolute;
  right: 30px;
  bottom: -10px;
  width: 0;
  height: 0;
  border-top : 10px solid red;
  border-right : 10px solid transparent;
  border-left: 10px solid transparent;
}