Guys kissing

definitely you have to tell your sister whats going on so she will know how to handle the situation and put it on the right path and to avoid possible complication and for her to guide her kid.

i think you should tell your sister what u've just seen, so that she may be aware of the real preference of your niece. that's all you can help to your sister.

please do!

WHAT THE!!!! That'll be my first impression... I don't ever wanna see something like that!!! Imagining it gives me the headaches! ANG SAKIT SA BANGS... (IT HURTS MY BANGS... expression in PHI)

I would tell her, but not make a huge deal out of it. Your sister needs to know, but you also dont want your neice mad at you.

Well its quite obvious that you should tell your sis about this issue to avoid any kind off trouble later on because its strange to see two guys making out and plus your niece is young and therefore as a responsible aunt you need to discuss this with your sis. Don't feel bad that after you tell your sis about this your niece is going to think bad of you. The other option you have would be to approach your niece on this issue first,make him see reason as to what his doing is not usually acceptable. All the very best to you on this:-)

Defenitely tell your sister.You should not hide any things from your sister and cause later problems in the future of your niece.Let her mother know about her,so that she can counsel and guide her daughter in the best way.