Non-consensual, in whatever way. This includes ignoring safewords, continuing on until the person is crying or upset (unless the 'ler knows for SURE ahead of time that the 'lee desires to be pushed to this point) or tickling anyone who didn't agree to it ahead of time. I don't think it matters if it's in public or not, most people aren't going to care unless you're literally tickling the person to the point they are being loud and causing a huge scene... depends on the situation, I guess. In general I'd say it's all good and fun unless you're touching someone who doesn't want you touching them or pushing them past where they want to go.