taxquery taxonomy get terms

so if $trips_list is the sample trips section, and you want the sample trips to only show trips with the same terms – you’d find the current trips term and argue that in your WP_Query.

// this trips terms
$tripTerms = wp_get_post_terms( get_the_ID(), 'reisezweck');

// if each trip only has one term (as its a location)
// we'll use the first of the array array of terms
// and we'll now have our current trips term
$tripTerm = $tripTerms[0]->slug;

// you can uncomment and use instead if it's possible a trip has multiple terms: 
// make an array of ID of current trips terms
/* $tripTerm = array();
foreach ($tripTerms as $aTripTerms) 
    $tripTerm[] = $aTripTerms->slug; */

$args = array(
    'post_type'     => 'ausfluge',
    'showposts'     => 3,
    'orderby'       => 'rand',
    'tax_query'     => array(
        array(
            'taxonomy' => 'reisezweck',
            'field'    => 'slug',
            'terms'    => $tripTerm,
        ),
    ),
);
$trips_list = new WP_Query( $args );

I’ve assumed each trip would have only one term. I’ve added commented code incase a trip could have multiple.