A Webhook can be used to ask your fellow channel members about a couple of alternative options. This is done by entering a question beginning with a keyword and some answer options like this:
!poll "Where do we want to go for the team event?" "To the pub" "Cooking event" "Laser tag"
Members answer by clicking on pre-defined reaction icons.
Just create an outgoing web hook listening on messages in all required channels, choose a trigger word ('!poll' in the example above) and insert and activate the Javascript from this Gist. You also need to add a URL (which is never called because the Javascript prevents it), it could, for example, be 'http://example.com'