There are multiple kissing scenes throughout the show, some between different sex couples and some between same sex couples. The whole premise of the show is focused on a teen who thinks she is in love with her best friend and realizes she is a lesbian after a seemingly passionate kiss is shared between them.
Towards the end of season one there is a relationship between two people and one of them is abstinent whilst the other one is quite hormonal, this is over quickly though
In the second season, a relationship between two males is quite sexual and they make many sexual remarks. Whilst on a date, they get into an argument, one of the males tells the waiter they will get a big tip, this is meant as a sexual innuendo. Whilst looking at wrestling males someone makes the remark 'these moves are so homoerotic, I'm surprised there isn't one called deep penetration' the trainer then replied 'there is, I'll show you'. The same couple get together after oral sex is implied between the both of them in an alley behind a gym.
In the second season finale, a man and woman kiss very passionately in the schools art room, they remove eachothers clothing so they are just in their underwear, sex is implied.
In the second season premiere, sex is implied between two characters, one of which climbs out the others window, we see them jumping down from the living room window, it is implied they are completely naked but it is blurred out.