SOURCE

<div class="odd-shadow">哎呦，猪先森</div>

.odd-shadow{
    margin-left: auto;
    margin-right: auto;
    width: 200px;
    height: 80px;
    border-radius: 8px;
    color: #fff;
    font-size: 24px;
    text-align: center;
    line-height: 80px;
    background: #06c;
    filter: drop-shadow(2px 2px 2px rgba(0,0,0,.8))
}

.odd-shadow::before {
   content: '';
    position: absolute;
    display: block;
    margin-left: -20px;
    transform: translateY(20px);
    width:0;
    height: 0;
    border: 10px solid transparent;
    border-right-color: #06c;
}