Yes and no. Sometimes its a joke that I mentally get but it wasn't really that funny so I might say "yeah I get that". If someone tells a joke that I don't even know what there talking about or why they think it is funny... I might laugh out of confusion... or I might just laugh to keep conversation moving.
Overall, sometimes I do sometimes I don't. You can probably tell by the way I laugh whether I think your joke is funny or not.