Simple categories matching happy:

• item,
• times,
• hormone,
• event,
• thing,
• stuff,
• hours,
• chemical,
• emotion,
• topic,
• neurotransmitter,
• love,
• occasion,
• thought,
• occurrence,
• message,
• ceremony,

Members with property happy:

• special_event,
• blooming_flower,
• moving_house,
• marriage,
• wedding,
• victory,
• birth,
• commencement,
• floating_cloud,
• graduation,
• apple,
• funeral,
• colour_yellow,
• christening,
• promotion,
• kitten,
• engagement,
• bar,
• winning_lottery,
• family_friend,
• delight,
• rich_harvest,
• movie_review,
• nice_wedding,
• winning_battle,
• pay_raise,
• game,
• joy,
• vacationing,
• picnic,
• delivery,
• homecoming,
• sister_wedding,
• unicorn,
• vacation,
• party,
• sleepover,
• good_breakfast,
• outing,
• inheritance,
• clown,
• decision,
• morning,
• sport_scores,
• baby_animal,
• puppy,
• friend_meeting,
• gathering,
• surprise_wedding,
• chemical_brother,
• flying_bird,
• noradrenaline,
• festival,
• goal,
• impending_wedding,
• serotonin,
• cult,
• young_love,
• butterfly,
• adoption,
• dopamine,
• surprise_party,
• strawberry_festival,
• celebration,
• childhood_toy,
• fanciful_idea,
• entrance,
• tree,
• great_festival,
• slapdash_vacation,
• job_promotion,
• no_wee,
• baby,
• economic_growth,
• bird,
• good_boy,
• laugh,
• shining_sun,
• television,
• baby_rattle,
• baby_naming,
• fuzzy_slipper,
• genocide,
• postal_worker,
• adrenaline,
• love,
• new_job,
• family_gathering,
• rainbow,
• mermaid,
• new_baby,
• game_night,
• wedding_undertone,
• professional_help,
• new_house,
• endorphin,