相合傘 (aiai gasa) means ‘to share one umbrella among two persons (esp. a couple)’.
Many kids (early teens) in Japan yearn for doing 相合傘 with their crush. It’s also common among kids to draw 相合傘 when they
(1) make fun of someone (e.g. two persons who look lovely together but not in a relationship)
(2) secretively make a wish on their notebook to be together with their crush.
(An Example of 相合傘 drawing below)
If I have a girlfriend, I wanna share an umbrella with her in a rainy day.