This tweet from @SenJohnMcCain received a barrage of spammy replies crammed with as many hashtags as possible. There's some variety, but all seem to contain #opmayflower2018. (Thanks @Shaun7559 for the tip.)
Looking at replies to McCain containing #opmayflower2018 results in 4808 tweets (including retweets) from 397 accounts; 983 original tweets from 47 accounts. The activity started at 6:30 PM Central on 5/11; volume is high for a little over an hour.
This table shows the frequency of the various hashtags included in the #opmayflower2018 tweets. We'll come back to the ones highlighted in blue (cyan?) later.