'He's a bit serious, isn't he?' 'Yeah, not exactly a barrel of laughs.'
be a barrel of laughs
To be fun, funny, and pleasant. Often used sarcastically to indicate that someone is unpleasant or not enjoyable to be around. A: "Is Mr. Grant always cranky?" B: "Oh, yeah—he's a real barrel of laughs!"I always have so much fun when Katie's around—she's a barrel of laughs!