Menu and SideBar Slides, Fades, and Hides I will admit that this code looks sloppy and repetitive. Which is why I'm asking how I can improve the efficiency and readability of this code.

// Sidebar tab highlight when clicked
$("#sidebar-tabs-container table td").click(function() {
  $("#sidebar-tabs-container table td").removeClass("sidebar-tab-selected");
  $(this).addClass("sidebar-tab-selected");
});



// poll and faq
// when faq question bar is clicked, slide down answer
$(document).on("click", ".question-container", function() {
$(".answer-container").stop().slideUp("fast");
$(this).parent().find(".answer-container").stop().slideToggle("fast");
});




// news and social feed





// activity
// activity new media content 
//media buttons click 
$(document).on("click", "#activity-media-icons-container span", function() {
    $("#activity-media-icons-container span").removeClass("activity-new-media-icon-  clicked");
$(this).addClass("activity-new-media-icon-clicked");
});

// show new media category and hide others depending on button clicked
$(document).on("click", "#new-media-images-button", function() {
   $("#activity-media-video-container, #activity-media-audio-container").slideUp(    function() {
   $("#activity-media-images-container").slideDown();
   });
});

$(document).on("click", "#new-media-videos-button", function() {
$("#activity-media-audio-container, #activity-media-images-container").slideUp( function() {
    $("#activity-media-video-container").slideDown();
});
});

$(document).on("click", "#new-media-audio-button", function() {
$("#activity-media-images-container, #activity-media-video-container").slideUp( function() {
    $("#activity-media-audio-container").slideDown();
});
});

/* show image link icon when hovered over image */
$(document).ajaxComplete(function() {
$(".media-image-buttons-container").hide();
});
// fade in image buttons on hover
$(document).on("mouseenter", "#media-content-container .media-image-container", function() {
$(this).children(".media-image-buttons-container").stop().fadeIn(200);
});
$(document).on("mouseleave", "#media-content-container .media-image-container", function() {
$(this).children(".media-image-buttons-container").stop().fadeOut(200);
});
This code can use quite a bit of work.


Run this code through a beautifier, ideally prior to posting it to codereview ;)
You are repeating yourself a lot, example : 



// Sidebar tab highlight when clicked
$("#sidebar-tabs-container table td").click(function() {
  $("#sidebar-tabs-container table td").removeClass("sidebar-tab-selected");
  $(this).addClass("sidebar-tab-selected");
});



Unless you have a dynamic number of sidebar tabs ( seems unlikely ), you can do the following.

var $sidebarTabs  = $('#sidebar-tabs-container table td');
var selectedClass = 'sidebar-tab-selected';

$sidebarTabs.click(function() {
  $sidebarTabs.removeClass( selectedClass );
  $(this).addClass( selectedClass );
});


The interesting part is that you do this type of code twice, so you could also write a helper.

function wireClassToggler( elements, className )
{
  elements.click(function()
  {
    elements.removeClass( className );
    $(this).addClass( className );
  });
}

wireClassToggler( $('#sidebar-tabs-container table td'), 'sidebar-tab-selected' );
wireClassToggler( $('#activity-media-icons-container span'), 'activity-new-media-icon-clicked' );


You also seem to use copy pasted code for the slideUp and slideDown functions, you should generalize that as well.