Photoshop can be used to create numerous vector artworks and there are numerous ways of creating this type of design. Also, it does depends, on your definition of an irregular shape. In the first example, use the pen tool found in the toolbar. Go to the top left and make sure it is in layer mode. Click the document in different locations. Hold down the mouse at certain points to curve the generated path. To complete (or close) the path, just click the start point. As the pen tool creates a path, there is nothing actually visible other than a few points (or as many as you like to create) so go to the path panel / panel and select the generated work path and go to the right side menu and fill with the current foreground color (set this to black via the toolbox). Once you are finished, make certain it is selected (use direct selection tool to select all the points) and then go to the edit menu and define command. https://youtu.be/PZL1TifkXv8
Instead of using the pen tool, use the next tool in the toolbox: freeform pen tool. Just select and then draw as you would with a normal pen. Personally it is easier to use an art pad / pen instead of a mouse (the example below was drawn using a mouse). Again, finish the creation of the path by meeting the start point. Go to the path panel and fill with a color or use the define custom shape command. You can draw truly weird and wonderful vector designs with the freeform tool. It is not the most elegant of tools but it does create some unusual and weird artworks. Another option to use to turn the design into a 'shape' is just to click the 'shape' button along the top option bar (this is with the most recent versions). The button converts it but does not save it as a vector preset. Repeat selecting multiple paths and defining those as a preset via the edit menu. Select the freeform pen tool in the toolbar. Draw using the freeform tool. Release mouse. Change fill and stroke. https://youtu.be/MWlLIGfFhMs
Very similar to the above approach but you can also set the magnetic option on for the freeform and it does create a very quick and easy way of creating unusual artwork as the tool has a tendency to randomly jump back and forth and on completion, the design is probably far more random than you could ever create just by sketching.
The CSH tool and others such as the rectangle, star etc can be used as a great source for designs. To do this, select one of the tools such as the rectangle tool and create a single rectangle. Go to the path operations (pathfinder in Adobe AI) along the top option bar/ control bar and set the option to 'combine' (or any of the others if you wish to subtract from the initial design) and then apply another rectangle and so on. Repeat the creation of the rectangle or circle or star etc multiple times and each path is then added to the original design. On completion, go to the edit menu and define to create the final preset (which can then be used multiple times throughout the application) https://youtu.be/36SwnfRpkjI
Not strictly involving any drawing but by using the edit menu and transform and warp command with a selected path (even a rectangle) then you can create a quick design in seconds. You might not achieve the most unusual vector with one pass of the warp tool as the warp grid is only 3 x 3. Select the individual points / nodes of the warp grid and warp the path in many different ways. Repeat and repeat until you achieve the result you want. The artwork can be stored as a preset (via the edit menu and define command) and re-used to create ever more complex graphics. Select the rectangle tool in toolbar. Select layer option in the top left. Create a rectangle. Go to the edit menu and use the transform warp command. Use the mesh to select and drag points and distort the rectangle and then click OK. https://youtu.be/v4louFcA20c
Not a vector but it can be turned into one. Layer. New layer. Select the brush tool in the toolbar. Set the color to black for the foreground. Select one of the basic default brushes (hardness 100%). Paint a tangled design of many brush strokes. Select menu. Load selection. Layer 1 transparency. Paths panel. Make work path (right side menu). Set tolerance and then click OK. Save work path (paths panel). Go to the edit menu and use the define command to save it as a preset for future use. https://youtu.be/V8A_Pib_82Y
You can now use the curvature tool which can be used to create all kinds of weird and wavy and curved designs. Select the tool, click on the document and then click elsewhere and continue and move the tool up and down and left and right to create the curve. The curves can be edited later using the direct selection tool as well as the curvature tool. https://youtu.be/DUN2oHk54C8
You can also Illustrator to create an unusual vector as the pen tools and filters and features can be used to create truly extreme artworks. Or use the brush tools and then copy it to Illustrator or another application with a vector trace tool (Corel trace etc) and use that to capture an unusual vector form that can be copied back into the application and again defined as a vector for future use.