The online version of MW has this additional definition of riff, which may be of some use to you:
a succinct usually witty comment
This was likely said in response to "it looks ominous." I would need more context, but I suspect that the comment "riffing" was said sarcastically. So the conversation might read more like:
"It looks ominous."
"Gee, what a ...
I think you are on track with your first suggestion: "to perform, deliver, or make use of a [musical] riff."
My first thought was, "it's a typo." But not being able to imagine what it could be a typo for, I'm going to go with the music option:
The first player makes his brilliant move and says, "It looks ominous."
The second player has two choices:
A "riff" is often associated with music.
A riff is thematic. It serves as the main musical idea for a (section of a) song. Often it's repeated and developed, sometimes with variations, sometimes in different keys, but always recognizable as the same main musical idea. Because a riff is a main theme for a song, it often becomes inextricably associated ...
You want a good reference for "Straphanger" one word, not two. Go read just about anything on MACVSOG in the Vietnam War, you'll find the term used multiple times by Recon Team members, also know as Spike Teams, they also had what was called Hatchet Teams, Reaction Teams, and others. The term is used often by the SF guys, and it's not use in a derogatory ...
It all depends on the context in which you use this term.
1) Trap Queen might refer to a song by Fetty Wap
She my trap queen
And in that case Trap is a place where drugs are sold.
2) A girl with large trapezius muscles.
Look at that girl hitting the gym, she's a real trap queen
3) the person is a queen for traps, with traps meaning boys dressing up ...
This phrase is exclusively used as slang (slang from AAVE as far as I can tell), so it's exact meaning can be hard to define. urban dictionary has several entries, and a lot of them have somewhat opposite meanings.
In general though:
A witty or street-smart female, usually with an urban flavor or appeal, who is loyal (potentially to a fault) and ...