N/A: I personally like this story a lot. Hope you all like it too.
Signs
Luffy knew the importance of following signs.
There was this one time when the crew were traveling. The path was so long and winding that everyone was getting irritable. Finally they spotted a long and winding path leading to building in the far distance. The pathway to the building that was too time-consuming to follow had a wooden arrow sign pointing toward the path and reading "This way to Hotel Creuser". There was also a sign on the grassy lawn in front of the building with a painted sign reading "Keep off the grass" but it was quite obvious it would have been quicker to cut through the grass. Being the eager and wayward captain he was, Luffy lead his crew through the grass instead of the path. This would have been a great idea if not for the lands mines they set off by cutting through the grass. The whole crew ended up running for their lives trying to avoid the sporadic explosions.
Then there was this other time when the Straw Hats were visiting a zoo. It was a great trip and all at least until Luffy decided to ignore the "Don't feed the two headed lions" sign. After he had feed them some meat they suddenly started to grow at an alarming rate. Then they escaped from their confinement and wreaked havoc on the whole zoo by destroying the cages of their other fellow animals. So you can imagine the whole crew trying to round up a bunch of winged horses, 8 legged tigers, one-eyed ostriches, flaming bullfrogs, and invisible snakes.
And still there was this other time. That the Straw hats were traveling through a misty jungle. They uncovered a stone sign written in some strange language. Robin deciphered it and it turned out that the sign read somewhere on the lines of "Do not enter". Again the ignoring the sign and not heeding the warning of his crewmate they ventured forward. It was going fine, that is until they discovered that they had entered the territory of some barbaric native village. Well you can guess what happened next. The straw hats got captured and were to become sacrifices to the god of the villagers. It was lucky that they managed to escape and narrowly escape death again.
Based on experience Luffy knew the importance of following signs. After all of those incidents with not following signs it was only likely that Luffy was cautious with signs. So when Luffy saw those printed block letters it was natural that he follow what they said.
He quickly snuck up the tall slim figure heralding the sign and kissed him on the lips.
"Luffy, what are you doing?" Sanji exclaimed as a blush seized his face.
"I'm just following the sign." He said innocently as he stared pointedly at Sanji's apron.
The white apron that Sanji had on read "Kiss the cook."