<human>: Context: I'm the newest and youngest person in my office. The co-worker (I'll call him Andrew) is much older than me but has always been nice to me asking how my weekend was, joining me at break etc. Andrew has been away for the week on business and I have been sharing my lunch with other co-workers who have also been nice to me.

However, these co-workers occasionally mock Andrew, express how they find him annoying or make comments about his weight. They also know Andrew talks to me frequently and seem to look at me like they wonder if I will tell him the things they have said. I have decided not to simply because I don't want to hurt Andrew's feelings.

My problem is that after hearing their comments I still feel kind of guilty and bothered by it because I didn't tell them to stop. Mind you, they tend to poke fun at everyone, not meaning to be harmful. Should I have said something though? How do I know they won't start making jokes about me when I'm not around? We all tend to share lunchtime together (including Andrew) so I don't want to avoid them. I'm just looking for some advice from anyone who has been in a similar situation and how to best handle it if gossip/mean jokes do come up.

Can you succinctly summarize the text in 1-3 sentences?
<bot>: Co-workers make fun of another co-worker I have casually befriended which makes me feel guilty/uncomfortable. How should I handle it?