Often implies using flattery or friendliness to win someone's favor for self-benefit. During the event, she cosied up to the influential guests to gain more contacts.
Pro Tip 2/3
Negative Connotation
Can suggest insincerity or manipulation, so be cautious when describing someone's actions. People noticed he only cosied up to the boss when he needed a favor.
Pro Tip 3/3
Strategic Relationships
Used to describe actions in social climbing or strategic networking situations. She's cosying up to the key players in her industry.