The phrase "gummy mess" usually refers to a sticky or messy situation or problem, like when something becomes tangled or difficult to deal with. Full definition
The longer it sets, the more the chia seeds are going to gel, and you'll have a clumpy, gummy mess on your hands! (screwedonstraight.net)
Also, please don't whip and beat your potatoes into a sticky gummy mess just because a recipe says to mix for 45 seconds. (sunnysideupsd.com)
Whereas water - based lubes often dry to a sticky, gummy mess on your hands, silicone lubes feel soft and powdery, so you can caress your partner's body and face without feeling like you're smearing spirit gum all over your lover. (tipsonlifeandlove.com)