<div class="container">
  <p>
    Regular button:
    <br />
    <a href="#" class="c-button">Looky here!</a>
  </p>
  
  <p>
    Fancier button:
    <br />
    <a href="#" class="c-button c-wing--left">How about here?</a>
  </p>
  
  <p>
    Another fancier button:
    <br />
    <a href="#" class="c-button c-wing--right">Or over there?</a>
  </p>
  
  <p>
    Even fancier button:
    <br />
    <a href="#" class="c-button c-wing--both">Why not both?</a>
  </p>
  
  <p>
    Now we're just being ridiculous:
    <br />
    <a href="#" class="c-button c-wing--both">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Recusandae voluptates officiis tenetur suscipit! Aspernatur quos quo, esse autem voluptates praesentium dolorem beatae tempora iure nemo, voluptatum vel doloremque maxime illum.</a>
  </p>
</div>

.container {
  max-width: 500px;
  margin: 30px auto;
  text-align: center;
}

.c-button {
  display: inline-block;
  position: relative;
  background-color: #333;
  color: #fff;
  text-decoration: none;
  padding: 10px;
  margin-bottom: 30px;
  
  &:hover {
    background-color: #000;
  }
}

.c-wing--left,
.c-wing--right {
  &:before, &:after {
    content: '';
    position: absolute;
    bottom: 0;
    height: 100%;
    width: 50px;
    background-color: inherit;
    z-index: -1;
  }
}

.c-wing--left {
  margin-left: 50px;

  &:after {
    display: none;
  }

  &:before {
    clip-path: polygon(0 0, 100% 0, 100% 115%);
    left: -49px;
  }
}

.c-wing--right {
  padding-right: 30px;

  &:before {
    display: none;
  }

  &:after {
    clip-path: polygon(100% 0, 0 0, 0 115%);
    right: -49px;
  }
}

.c-wing--both {
  @extend .c-wing--left;
  @extend .c-wing--right;

  &:before, &:after {
    display: block;
    z-index: 1;
  }

  margin: 0;
  padding: 15px 30px;
}