Edit in JSFiddle

$(function() {
	
	$('table').each(function() {
		
		var head_col_count =  $(this).find('th').size();
		for ( i=0; i <= head_col_count; i++ )  {
			
			var head_col_label = $(this).find('th:nth-child('+ i +')').text();
			$(this).find('tr td:nth-child('+ i +')').attr('data-th',head_col_label					);
		
	}
		
	})
	
});
<table>

    <thead>
        <tr>
            <th>TIME</th>
            <th>PERFORMER/EVENT</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>7pm</td>
            <td>TBD</td>
        </tr>
        <tr>
            <td>7:45pm</td>
            <td>Irish Whiskey Tasting Contest<em>(Must be 21 years old w/ approved wristband)</em></td>
        </tr>
        <tr>
            <td height="36">8:15pm</td>
            <td>TBD</td>
      </tr>
    </tbody>
</table>
	
<hr />
    
    	<table>

    <thead>
        <tr>
            <th>TIME2</th>
            <th>Test 2</th>
            <th>PERFORMER/EVENT2</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>7pm</td>
            <td>1</td>
            <td>TBD</td>
        </tr>
        <tr>
            <td>7:45pm</td>
            <td>2</td>
            <td>Irish Whiskey Tasting Contest<em>(Must be 21 years old w/ approved wristband)</em></td>
        </tr>
        <tr>
            <td height="36">8:15pm</td>
            <td>3</td>
            <td>TBD</td>
      </tr>
    </tbody>
</table>
<hr />
    	<table>
    	  <thead>
    	    <tr>
    	      <th>TIME3</th>
    	      <th>PERFORMER/EVENT3</th>
  	      </tr>
  	    </thead>
    	  <tbody>
    	    <tr>
    	      <td>7pm</td>
    	      <td>TBD</td>
  	      </tr>
    	    <tr>
    	      <td>7:45pm</td>
    	      <td>Irish Whiskey Tasting Contest<em>(Must be 21 years old w/ approved wristband)</em></td>
  	      </tr>
    	    <tr>
    	      <td height="36">8:15pm</td>
    	      <td>TBD</td>
  	      </tr>
  	    </tbody>
  	  </table>
<hr />
<table>
  <thead>
    <tr>
      <th>TIME4</th>
      <th>PERFORMER/EVENT4</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>7pm</td>
      <td>TBD</td>
    </tr>
    <tr>
      <td>7:45pm</td>
      <td>Irish Whiskey Tasting Contest<em>(Must be 21 years old w/ approved wristband)</em></td>
    </tr>
    <tr>
      <td height="36">8:15pm</td>
      <td>TBD</td>
    </tr>
  </tbody>
</table>
table { 
  width:100%; 
  border-collapse:collapse; 
}

@media only screen and (max-width:550px) {

	table, thead, tbody, th, td, tr {display: block;}
    th {display:none;}
	tr:first-child {
		border-top:none;
		margin-bottom:0;
	}
	tr {
		border-top:1px solid #ccc;
		border-right:1px solid #ccc;
		border-left:1px solid #ccc;
		margin-bottom:5px;
	}
    td {
        border: none;
        border-bottom: 1px solid #ccc;
        position: relative  !important;
        padding-left: 50% !important;
        white-space: normal;
        text-align:right  !important;
    }
    td:before {
        padding-right: 10px;
        white-space: nowrap;
        text-align:left;
        font-weight: bold;
    }
    td:before {
        content: attr(data-th)":";
		position:absolute;
		left:5px;
    }

}