I'm sure there are other ways to accomplish this, but one solution would be to use join through the Query Builder.
If you have tables set up something like this:
users
id
...
friends
id
user_id
friend_id
...
votes, comments and status_updates (3 tables)
id
user_id
....
In your User model:
class User extends Eloquent {
public function friends()
{
return $this->hasMany('Friend');
}
}
In your Friend model:
class Friend extends Eloquent {
public function user()
{
return $this->belongsTo('User');
}
}
Then, to gather all the votes for the friends of the user with the id of 1, you could run this query:
$user = User::find(1);
$friends_votes = $user->friends()
->with('user') // bring along details of the friend
->join('votes', 'votes.user_id', '=', 'friends.friend_id')
->get(['votes.*']); // exclude extra details from friends table
Run the same join for the comments and status_updates tables. If you would like votes, comments, and status_updates to be in one chronological list, you can merge the resulting three collections into one and then sort the merged collection.
Edit
To get votes, comments, and status updates in one query, you could build up each query and then union the results. Unfortunately, this doesn't seem to work if we use the Eloquent hasMany relationship (see comments for this question for a discussion of that problem) so we have to modify to queries to use where instead:
$friends_votes =
DB::table('friends')->where('friends.user_id','1')
->join('votes', 'votes.user_id', '=', 'friends.friend_id');
$friends_comments =
DB::table('friends')->where('friends.user_id','1')
->join('comments', 'comments.user_id', '=', 'friends.friend_id');
$friends_status_updates =
DB::table('status_updates')->where('status_updates.user_id','1')
->join('friends', 'status_updates.user_id', '=', 'friends.friend_id');
$friends_events =
$friends_votes
->union($friends_comments)
->union($friends_status_updates)
->get();
At this point, though, our query is getting a bit hairy, so a polymorphic relationship with and an extra table (like DefiniteIntegral suggests below) might be a better idea.