很赞, 好棒, 糟糕.
Right now I only know three. I'm sure you know others; please share!
Just to let you know, 口語 just means "spoken language". The Chinese for slang is 俚語.
There is so much Chinese slang and 網絡用語 (internet language), and I feel like there is new slang out almost every week, so it can be hard to keep up, but I guess there are two main categories - words that come from dialects and have now become standard Mandarin, and words that have come from the internet.
忒 is Beijing dialect for 太
咋 is Dongbei dialect for 怎麼
倍兒 is Beijing dialect for 很
Some popular slang from 2018 (that I'm aware of) includes:
小豬佩奇身上紋，掌聲送給社會人 - You need to google this one, it's a long story.
Diss - from the English
確認過眼神 - To gaze into someone's eyes, from a popular song
SKR - something a Chinese star called 吳亦凡 said on a rap show. I still don't think anyone knows what this means
陳獨秀同學請坐下 - a reference to a co-founder of the CCP and the editor of a popular magazine in the 1920s called "New Youth" 《新青年》, you often see it on Weibo when someone wants to say that someone's comment is really excellent, and if often sarcastic
杠精 - An argumentative person, often just for the safe of arguing
皮一下，很開心 Used when someone is a bit naughty, but accidentally caused something bad/unexpected to happen.
佛系 Used to describe someone very "Otaku" 很宅
小奶狗/小狼狗 Words for teenage boys/girls
If you read something like this http://www.sohu.com/a/212622723_99922357 it will give you a list of slang by year. Some of these are still commonly used, like 療妹, but others I haven't heard since, like 扎心了，老鐵.
I hope this helps
很帅 very handsome
好可爱=很可爱 soooooo cute
Hehe I'm not going to share all my baggage of Chinese slang here as I don't want to be banned on this platform. But I'll leave you with some phrases I like:
你的良心不会疼吗？Literally "Has this action ever given you a slash of conscience?" Don't you feel sorry about that?
好人卡 "nice guy card", it's about those always nices guys who were friendzoned
辣眼睛 I want to unsee it!
为什么放弃治疗？is a more artistic^^ way to say 有病了吗？which means "Why did you give up your treatment?"
Ohh, I thought 倍兒 is used only in Tianjin:) new info 倍儿好！