Change pronouns in BuddyPress' "changed their profile picture" activity item.

gistfile1.php

<?php
add_filter( 'bp_xprofile_format_activity_action_new_avatar', 'djpaul_change_pronouns', 10, 2 );

function djpaul_change_pronouns( $action, $activity ) {
	$userlink = bp_core_get_userlink( $activity->user_id );

	// Change this to decide between male/female, etc.
	if ( true ) {
 		$action = sprintf( __( '%s changed her profile picture', 'buddypress' ), $userlink );
	} else {
		$action = sprintf( __( '%s changed his profile picture', 'buddypress' ), $userlink );
	}

	return $action;
}