Dear Rabbi Simon,
What is your opinion about opening cans on Shabbos?
This is a complex question, which I will answer succinctly on this occasion. In brief, I don’t favour it, in accordance with the view of Rav Moshe Feinstein (and others). For this reason we generally don’t buy cans of beer or soft drinks for use on Shabbos at Kesher. However when they occasionally appear for whatever the reason, I allow them to be used, as many authorities are lenient. In such a case, it is best to empty the contents into a glass rather than to drink from the can directly (this is for halakhic reasons, beyond considerations of etiquette).
The type of can requiring a can opener (rather than “pop-top”): best to puncture top and bottom of can simultaneously.
Rabbi Rashi Simon