How do you warm up your expressed milk when you’re out?

Molls

I hope this isn’t a dumb question but I’m a first time mom and my little babe is only 2 weeks old.

We are going out with family tonight and I would just rather bring a bottle of breast milk rather than trying to nurse right in the restaurant.

How do you moms warm up your milk when you’re out? Or do/can you just give it to baby when it’s still cold?