Weeds.

Pesky things. Annoying things that show up long after you think that you have gotten rid of long ago. You use everything you can think of to prevent the determined ones from reappearing. Pesticides, pulling them by the roots, putting your plants in good soil to prevent them from seeding, but sometimes they still pop up.
There are numerous things in high school that can be compared to weeds, bad scores on tests that haunt you at the end of the term, the dumb decision you made at a party, the last guy you dated or talked to, rumors that refuse to die. When any of these things bud once again, it tends to ruin your day. Some are able to take it like a grain of salt, pull it out, and keep on gardening. Others, including myself, tend to dwell on these things and allow it to damper the beauty of your flowers. Even after it is pulled out, the hole where it was rooted is a constant reminder for the rest of the day that it was there. People were talking about it, and it is never a good feeling knowing that others were speaking of you behind your back and it was not in the best light. Often, these weeds come up because they are the tool of some individuals to drain your day, your pretty flowers of their colors.
I picture something like this:
Your neighbor sees you hard at work on your magnificent garden. They turn around and look at theirs to see that it is okay, nothing too spectacular but not too shabby. Then suddenly. they see the green on their thumb spreading, up their arms until they are engulfed in the green of envy. They want your garden, but they can not have it. Faced with this dilemma, they think of the next best solution, if they can not have your garden, they will ruin yours until theirs is better by comparison. Not wanting to be caught red-handed, they think of ways that will slowly eat away at your garden's beauty. Weeds. Tossing them over the fence every time they get a chance. The next thing your neighbor does is they sit back and watch the destruction take place.
This is what people in high school are doing when they bring up things from their past. They just want to ruin your day, ruin the image others have of you in their mind. Do not let them. Just pull out those weeds, and continue on. Now as badly as you may want to throw them back over the fence, it is probably not worth it. Be the bigger person, their garden is probably pitiful in comparison anyways and they need all the help they can get.
JSL