a period of time spent doing a lot of an enjoyable activity, for example spending time with friends, watching television, or drinking alcohol

You and me need a big catch-up sesh over coffee! 你和我需要喝杯咖啡，好好叙叙旧！

I'm just having a couple of beers. I'm not getting involved in another big sesh. 我只是来喝点啤酒，不想参加大张旗鼓的派对。