Conceptual art in St-Petersburg: What does this mean?

Around 3 years ago, people strolling along St-Petersburg streets could see these strange paper posters attached to walls. Each of them contained some short but intriguing and mystifying phrase. Startled people started to take photos of these papers and to post them on Internet, while asking each other: "Do you know what all that means?".
Here are these strange posters. Imagine you walking on the street and seeing these things:

"Better than nothing" is worse than "just cool". 

Tourists are freaking performance

The winter's come, the winter's gone, but summer is the summer. 

You remember, you are proud, then tell us what you're proud of

(It refers to the famous slogan of the social advertising campaign launched before the anniversary of the 1945 victory of Russia over the Nazi Germany: "I remember, I'm proud". It was the real epidemic campaign -  so-called "Georgian ribbons" (orange and black striped ribbons of color of the highest military Russian award, St. George's order) were spread among all people, distributed in schools, workplaces, just on the streets. People attached them on their cars, bags, clothes, to show that they remember veterans, but due to this immense popularity it soon became a vice: teenagers decorated themselves by these ribbons, but they didn't know anything about the Great Patriotic War). 

I'll buy, I'll sell, I'll get profit

However, the secret was quickly disclosed, because the author hadn't even thought of remaining anonymous.
Agon_noga is the street art activist from St-Petersburg. His works created in the conceptual style, aren't aimed for high artistic value. Their purpose is the close interaction with viewers. So, the artist fully achieved this goal.