They seem to be Internet slangs but I can't figure out what the meaning is. For example here
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The person who buys the company shares you are selling is the 接盘
Metaphorically, 接盘侠 is a man, 侠, who 接盘s
A is a loose woman, B and others are her lovers, maybe she gets pregnant, B does not want her, so she looks for C or D or E, seems to love him, asks if he wants to marry her, has sex with him then says, "OMG, I'm pregnant!"
接盘侠 is 喜当爹
喜当爹：a man who is not so interesting, likes a woman, the woman is aloof, but eventually comes back to him, because she is pregnant. She marries him because her socially and otherwise more attractive boyfriend doesn't want her, or can't, for family reasons, have her.
接盘 and 接盘侠; I think those terms come from Stock Market.
Basically, 接盘 means you buy the shares/stocks from others. Metaphorically, it could mean you get something from others. 接盘侠 is kind of person who seems to always get the higher price of stocks from others. Let's say when the stock goes very high, but there are still someone who believes it could go higher and then they buy it. And finally, the stock plummets. Those, who operate like that, are called 接盘侠. 接盘侠 can refer to those who are fooled/tricked to get something (usually not good or higher price than it deserves) from others.
In your context, "让我以后不要找中国男人接盘" means she is suggested that she should not find other Chinese men for dating, so as not to propagate those bad stuff (low IQ, dirty and etc as mentioned in the context) from his previous black boyfriend. And things could be worse if she gets pregnant and then find another Chinese guy to 接盘. It's really insulting. Those bad languages are used to humiliate her.
Etymologically, “大盘” started to be used in the context of stock exchange. Literally “big plate”, it means the collective whole of the stocks. As stock prices are always believed to be manipulated, prices experience unreasoned risings and fallings along the history. For those who bought stocks when the prices were very high but then fell terribly and could hardly reach that high again, their buy-in activity and the prices going low, jointly, is called 接盘 — to take over something not as good as perceived which costs much more than its real value/quality.
Somehow kind of materialization, when a man finds that his wife was not virgin when they married, or, when a man finds that his son was conceived by another man’s sperm, he can be called a 接盘侠.
The character 接 means receive, accept. The original meaning of 盘 here likes that in 大盘 or 大盘股, means large stocks, large share in stock market. The character 侠 means heroic/valiant hero who have sense of justice in Chinese knight errant novel, and also used as a suffix for person's title currently. 接盘 means 高价买进股票 buy stocks at a high prices, so 接盘侠 means people who buy stocks at a high prices, or literally means the large stocks accepter. It later also represent the man who takes over a promiscuous girlfriend, even she once aborted baby, or married a pregnant girlfriend and accept and raise her baby. 接盘侠 represents the person who takes over some awful / horrible mess or some troublesome things unwittingly for being cheated.